truths as the first and greatest aim of science, we may, perhaps, take next some of Francis Bacon's more practical ideas about the objects and aims of science; to increase man's sovereignty over Nature, to compel Nature to be subservient to his will, and to minister to his wants; to restore his lost sovereignty over Creation. And, indeed, when the new truths are discovered, they are soon applied to practical purposes, and to furthering the material good of mankind; but to study science with this object alone is usually pernicious, and always to be avoided.

Some of you will ask me the more direct use of science. I fear I cannot tell you much about this; I would rather refer you to some of the enthusiastic-I hope not exaggerated- articles which have appeared from time to time during the last few years in various journals and magazines. It is directly useful for the purpose of science scholarships at the Universities, which are much on the increase; also it forms a part of the examinations at Woolwich, and for the Civil Service. Scientific appointments are year by year becoming more numerous in this country and in India. Indirectly, science is useful to every one. I say I cannot tell you much about its direct and practical uses, because I believe that the main use of it is to cultivate a certain set of mental faculties, to induce a certain mode of thought. The modes, and tones, and phases of mental action are as diverse as the modes of bodily action, and just as we exercise one set of muscles by rowing, another by riding, and a third by walking, so do we exercise a certain set of faculties when we study classics, another set when we study mathematics, and a third when we study sciences. The cultivation of this habit of thought engenders among other things a habit of observation and a spirit of inquiry. Questions suggest themselves daily, for an answer to which we must apply to science. Why do winds blow and storms rage? What are day and night, summer and winter, sunshine and frost? Of certain common things we rarely think, or if we do we assign the simplest meaning to them. For how many centuries did not mankind believe the world to be flat, the sun to be a globe of fire quenched nightly in the western sea, the sky to be solid, and the stars set into it like gems! Savages still believe that the firmament is a solid dome, and the sun and moon living creatures who walk across it.

The third of our four divisions concerns the methods we shall follow in our study of the sciences discussed above. Firstly :lectures. It is essential that you should see the various changes wrought upon or within matter; not alone hear about them or read of them. You must not only observe, but you must think of the experimental results; understand them; understand the means by which they are brought about. It will be well for you to take notes, roughly at first, to be copied out afterward, and extended from memory. It is a mistake to take very full notes during a lecture. They may become an almost verbatim report of the lecture; the spirit of the matter is lost because the mind is fixed upon a detail. Experiments also are often lost; and at the end a mass of writing remains, but no knowledge of the work done. It is preferable to write down headings of subjects; the pith and marrow of the subject matter only;-in a word, to make merely an outline of the picture, and to fill in the details afterwards from memory. Sketches of appa ratus are always desired among the notes, also any general remarks, and queries. At the end of each lecture you will be questioned, and at the commencement of each lecture the matter of the preceding lecture will be recapitulated; at this time also your own queries will be answered. It is important that you should not allow any subject to be partially understood, or misunderstood. Make a note of any difficulty, and let it be cleared up at the commencement of the next lecture, or at some intermediate time. The misunderstanding of one important fact may render the right understanding of succeeding matter nearly impossible. Then, later in the half, I should like you to read in text-books about the subject of your lectures, and thus to supplement the lecture-work by book-work. The advantage of this will be very apparent when you are examined.

What we desire is that science shall grow up side by side with your other subjects of study, and enter into your daily life. It is thus only that it can possess any real vitality. And if any subject of study possesses not vitality-intense, active, exuberant vitality—it languishes, becomes unhealthy, weak, and ultimately useless. It resembles a tree which loses first one branch, then another, and then dies entirely. And when upon the tree of knowledge a new branch is grafted, we desire to see it growing up side by side with the great branches already there. Our school knowledge-the knowledge which in its entirety ful

fils the conditions of that comprehensive word culture-must be one and undivided; hence a new subject can only flourish when it is woven completely into our school life, when it ceases to be regarded as a something extraneous and beyond the pale. I hope none of you are like the doctors of Salamanca when they were confronted with Columbus, or like the cardinals who passed judgment upon Jordano Bruno and Galileo.

I must add one word in conclusion as to the attitude of mind most conducive to a right study of natural science. In the first place it is necessary to free the mind from previous ideas and conjectures, and to neglect the evidence of the senses unsupported by extraneous means; thus the earth seems to be flat, and the sun to be a glowing disc which moves around it, yet research has proved that our senses here deceive us. Again, how difficult it is to realise the fact that two sounds may produce silence, two lights darkness, until it is experimentally proved that such is the case. It is hard to believe that the force which manifests itself by attracting light bodies when amber is rubbed, is identical with lightning, yet such has been proved to be the fact. We must clear our minds from preconceived opinions before we can profit much by the teachings of science.

Do not be discouraged by the apparent difficulty of science at starting; all things newly presented to the mind require the exercise of some effort before they can be grasped. If the current of our thoughts is to be diverted into a new channel, it must needs require some time to change it from its old course. Comfort yourselves with the knowledge that at the outset you know more true natural science than did Aristotle and all the great philosophers of antiquity. The very science which you learn almost as soon as you know the alphabet, the fundamental ideas about the earth, the sun, the moon, the air, places you at starting ahead, in the matter of science, of the flower of Middle Age erudition: Professors of the Sorbonne, Doctors of Salamanca, Monsignori of the Sacred College. If, at first, the path of science seems to wind uphill all the way, remember that when the toil is over the view from the summit is very glorious. The sun rises upon a new land infinitely vast, infinitely fertile; full of streams by the side of which you may wander, and see all nature reflected in their pure depths.

Above all things, I would ask you to study science reverently. Many of our studies concern the works of man, here we are dealing with the works of God, governed directly by His laws. Surely then it behoves us to bow our heads as we enter the portal of Nature, to be possessed of infinite humility, to assume no prying spirit of curiosity, to have no intellectual pride. Some of you no doubt remember Rembrandt's picture of the "Anatomic Lesson," and the calm, reverent, inquiring look of the students who surround the dead man; a sort of awe in the presence of the wonderful mechanism of the microcosm Man, as we must have awe in the presence of the macrocosm Nature. A something almost akin to the deisedaimonia of the Ancients; a reverential fear of that which is obscure, and but partly manifest. I know not whether the smaller and more obscure works of God do not convey this even more than those which are immeasurably greater. S. Augustine says, "Deus est magnus in magnis, maximus autem in mini nis." We are scarcely more awed by the myriad stars and suns and systems around us than by the myriad atoms of which the smallest mass of matter consists, and which possess functions, attributes, actions, as definite in character, as varied in form, and as absolutely governed by immutable laws, as the members of systems comprising a million worlds, ten million miles away.

ZOOLOGICAL RESULTS OF THE 1870 DREDGING EXPEDITION OF THE YACHT“ NORNA” OFF THE COAST OF SPAIN AND PORTUGAL*

AT the last meeting of this Association, held at Liverpool, I exhibited as one of the trophies of the Norna Expedition

a new silicious sponge, to which I gave the name of Pheronema Grayi, or "the Portuguese Bird's-Nest Sponge ;" and on this occasion the following is a brief synopsis of other leading novelties and more general results of the dredging cruise. A few preliminary remarks on the origin and object of the expedition may preface this synopsis.

*Communicated to the Biological Section of the British Association, Edinburgh, August 8, 1871.

To Mr. Marshall Hall, F.G.S., &c., who personally superintended the expedition, are due the thanks of the scientific world for having so generously devoted his yacht Norna to the purpose of scientific discovery. This gentleman had early in the year conceived the project of rendering science that service it is to be regretted so few owners of yachts are disposed to contribute; and to him I feel myself under the deepest obligations for the opportunities afforded me during this cruise of acquiring that practical information so keenly appreciated by every working naturalist. Nor must I forget here to associate with his the name of Mr. Henry Lee, F.L.S., the worthy president of the Croydon Microscopical Society, as one of the chief instigators of the scheme, and the person to whom I am especially indebted for my introduction to Mr. Marshall Hall, as one likely to make the most of the opportunities that would be afforded.

Having accepted the last-named gentleman's kind invitation to accompany him as naturalist in a small way to the expedition, it was decided I should memorialise the Council of the Royal Society for a grant to defray the heavier expenses of dredging and collecting apparatus. My application was most favourably received, thanks to the numerous kind scientific friends who sup. ported it, and a sum of 50!. was immediately placed at our disposal for the purpose required. My indebtedness to the Royal Society for this liberal assistance has already been acknowledged, thongh I cannot permit so fit an occasion as the present to pass without once more endorsing it.

By the middle of May everything was prepared, the Trustees of the British Museum, on the especial recommendation of Professor Owen and Mr. Waterhouse, extending me an extra three weeks' leave of absence. The companionship and services of Mr. Edward Fielding were also fortunately secured, whose earlier dredging experiences with Mr. M'Andrew in the Red Sea seemed calculated, as they afterwards proved, to be of the most valuable assistance. Our time being limited, the west coast of Spain and Portugal was decided upon as a locality likely to yield us the most satisfactory zoological results, and on the recommendation of Mr. Henry Woodward we resolved first to proceed to Vigo Bay, where, in company with his lamented brother, Dr. S. P. Woodward, and Mr. M'Andrew, he had in the year 1856 obtained such abundant and valuable material. From thence it was proposed we should work our way down to Lisbon, our particular ambition being to reach the deep-sea fishing ground off Setubal, some twenty miles further south, from whence Prof. du Bocage, the talented conservator of the Lisbon Museum, had obtained specimens of the "Glass Rope Sponge" (Hyalonema), and numerous other novel treasures. On starting, we touched and remained a couple of days at Guernsey, and at that spot a few hours spent in shore-collecting rewarded us with the earliest substantial fruits of the expedition; seven more days brought us to Vigo, the point which constituted the first basis of our practical dredging operation".

A detailed list of the numerous species collected throughout the cruise being in course of preparation for the more technical and exhaustive report to be presented to the Royal Society, I here propose, commencing at the lowest animal group, to briefly enumerate some of the more important forms taken, adding such remarks on the characters or connecting circumstances which render them more especially deserving of attention. Of all, the subkingdom of the Protozoa has perhaps furnished us with the most abundant and valuable material, the sponge class in particular contributing many novelties. Before leaving British waters even, the few hours spent in shore-collecting at Guernsey, already alluded to, resulted in the accession of three new species of the genera Isodictya and Hymeniacidon, which I have placed at the disposal of my kind friend Dr. Bowerbank to be described by him in his supplementary volume of the "British Spongiada," now closely approaching completion. The moderate depths within the Laminarian and Coralline zones, from the shore line down to fifty fathoms, at which we collected and dredged in Vigo Bay, and afterwards further south in the neighbourhood of Setubal and the Sado river, proved remarkably productive of species belonging to the same group, as also to that of the Calcarea or calcareous spiculed sponges including Sycon and Grantia, &c. The most interesting of any, however, were the species belonging to the Hexactinellidae, or hexradiate spiculed sponges, of which the beautiful Euplectella and Hyalonema form familiar examples. Nine species belonging to this group were obtained at a depth varying from 400 to 800 fathoms off Cape Espichel and Cezimbra, including Hyalonema, Dactylocalyx, Aphrocallistes Bocagii, Lanuginella pupa, and four other species new to science, three out of which necessarily constitute the types of new genera, the residue

again furnishing data enabling us better to appreciate the characters and distinctions of those previously made known to us. The form belonging to the same group, and described by myself as Pheronema Grayi, and exhibited at the last meeting of this Association, is the most conspicuous among all these on account of its size, and I would here add a few more words in reference to this particular type. Since last year I have been afforded the opportunity of examining and comparing my own with numerous specimens of Prof. Wyville Thomson's Holtenia Carpenteri taken in the North Sea and also in the Atlantic, and from an evolu. tionist's point of view, this examination has led me to regard my specimens as holding rather the rank of a well-marked local variety than of a distinct species as I at first premised. A comparison of the specimens, now placed side by side in the British Museum collection, will, I think, suffice to prove to all those inte. rested in this subject how strongly marked as varieties these two forms are. Meanwhile, the generic name of Pheronema adopted by myself I still retain, as I consider both Prof. Wyville Thomson's form and my own to be local varieties of another species first described by Dr. Leidy of Philadelphia as Pheronema anna, and a letter recently received from Dr. Leidy himself more fully convinces me of this, though he has not yet bestowed on it the minute microscopical investigation of its structure needed for the effectual clearing up of this, at present, doubtful point.

In my description of other sponges belonging to this same Hexactinellate group, read before the Royal Microscopical Society, and published in their "Transactions" for November 1870, I have, in fcreating a new genus and species, Askonema setubalense, erroneously associated Prof. Thomson's name with it as having once pronounced the form to be of vegetable and not animal organisation. The mistake arose from the misconception of a name singularly similar in euphony as pronounced to me by Prof. du Bocage, and I here avail myself of the oppor. tunity of rendering Prof. Wyville Thomson that amende honorable Í feel myself in duty bound to accord to him.

Passing next to the class of the Foraminifera, our gatherings have been remarkably rich both from the coralline and abyssal zones, the latter furnishing us with numerous arenaceous types (Rhabdomina, &c.), and the former being notably abundant in species and varieties of Lagena and Cristellaria. Many of these forms are new to science and await description, and I must not forget to acknowledge here my indebtedness to Mr. Henry Lee for the very great assistance he has rendered me in his skilful preparation of the various gatherings of these minute organisms. To Mr. Henry Hailes also my best thanks are due for similar services.

The Colenterate sub kingdom has likewise furnished several new and rare forms, including among the latter category an example of Hyalopathes pyramidalis, M. Edw., one of the Antipathiidee now represented for the first time in our national collection, if not in this country. In the Alcyonarian group, Veritillum cynomorium, first taken sparingly in Vigo Bay, and afterwards abundantly in the Laminarian zone near Setubal, excited our warmest admiration.

Nothing can exceed the beauty of the elegant opaline polypes of this zoophyte when fully expanded, and clustered like flowers on their orange-coloured stalk; a beauty, however, almost equalled by night when, on the slightest irritation, the whole colony glows from one extremity to the other with undulating waves of pale green phosphoric light. A large bucketful of these Alcyonaria was experimentally stirred up one dark evening, and the brilliant luminosity evolved produced a spectacle too brilliant for words to describe. The supporting stem appeared always to be the chief seat of these phosphorescent properties, and from thence the scintillations travelled onwards to the bodies of the polypes themselves. Some of the specimens of this magnificent zoophyte measured as much as ten inches from the proximal to the distal extremity of the supporting stalk, while the individual polypes, when fully exserted, protruded upwards of an inch-anda-half from this inflated stalk, and measured as much as an inch in the diameter of their expanded tentacular discs.

Numerous polyzoa were also dredged up from the various depths, many of which remain yet to be identified; but the allied group of the Tunicata has perhaps furnished by far the most interesting material of the whole molluscoidan sub-kingdom; surface-skimmings one morning near the mouth of the Sado river having rewarded us with numerous specimens of an Appendicu laria, which, from notes and sketches made at the time of their capture, I have since found to have presented phenomena seemingly not yet observed by any other naturalist. Hitherto these organisms have been presumed to constitute a distinct genus of

analogies were seemingly strengthened by the increased knowledge which gradually arose concerning the various parasitic maladies to which man and the lower animals were liable. Writing in 1839, Sir Henry Holland says in his essay "On the Hypothesis of Insect-life as a Cause of Disease,' "The question is, what weight we may attach to the opinion that certain diseases, and especially some of epidemic and contagious kind, are derived from minute forms of animal life existing in the atmosphere under particular circumstances, and capable, by application to the lining membranes or other parts, of acting as a virus on the human body." Now, the fact of the multiplication of the virus within the body was the peculiarity of these diseases, which, above all others, caused such an hypothesis to be received with favour. Causes which are specific, and which seem capable of self-multiplication-what can such agents be but living things of some kind, plant or animal? This mode of argument was with many all-powerful. And when, after the discovery of the yeastplant by Schwann, in 1836, new doctrines concerning fermentation began to prevail, the views of those who believed in the living nature of the specific causes of epidemic diseases were in part strengthened. If all fermentations were initiated by the agency of living organisms, and the specific diseases were comparable to processes of fermentation, then how natural was it that many who were moreover influenced by the other analogies, should be led to imagine that the specific causes of these diseases were also living organisms. Only now, attention became directed to the much lower organisms which are so 'frequently as▪ sociated with fermentative and putrefactive changes, instead of to insects "minute beyond the reach of all sense."

Here, then, is the origin of what in modern times has been termed "The Germ-Theory of Disease." Like homeopathy and phrenology, this theory carried with it a kind of simplicity and attractiveness, which insured its acceptability to the minds of many. But, however, it seems to rest upon foundations only a little more worthy of consideration than those upon which these other theories are based. Now, owing to its influence, in combination with the more generally received doctrines concerning the origin of life, there has gradually grown up an unwillingness in the minds of many to believe that these contagious diseases can arise de novo. And this being one of those theories which tends to curb inquiry, and to check the possible growth of sanitary knowledge in certain highly important directions, it seems to me necessary to look with scrutinising care to its foundations, not only with the view to the advancement of medical science, but with the direct object of removing all checks which may exist to the growth of sanitary precautions against the origin of these most pestilential affections.

Let us see, then, how far the "theory" fulfils the conditions which all good theories do fulfil-how far it explains a great number of the phenomena in question, without being irreconcilable with others.

The advocates of the "germ-theory" have always rested their belief in it, in the main, because they considered that it offered a ready explanation of the increase of the virus of the contagious diseases within the body of the affected person. This increase they suppose is not otherwise to be explained. All other considerations brought forward in support of the theory are just as explicable by another supposition. Fully admitting that the occurrence of a process of organic self-reproduction would be a very adequate way of accounting for the increase of the infecting material, we must see whether this mere hypothesis can be reconciled with other characteristics of these affections. In the first place, it may be asked, whether such a process is actually known to constitute the essence of any general diseases. Because, if so, those in which it does occur, ought, in the event of the hypothesis being true, to present a close similarity to the diseases in which such a process is supposed to occur.

Now, there are certain general diseases which do undoubtedly depend upon the presence and multiplication of organisms in the blood and throughout the tissues generally. There is the epidemic and highly contagious distemper amongst cattle, known in this country by the name of the " blood," and which excites in man that most dangerous morbid condition called "malignant pustule.' The researches of M. Davaine and others have revealed the fact that this disease is essentially dependent upon the presence and multiplication of living organisms, closely allied to Vibriones, in the blood of the animals affected, and that similar organisms are also locally most abundant in the contagiously incited."malignant pustule" of man. Unless this latter is

• See Comp Rend 1864 and 1865

destroyed in its early stages, the contained organisms spread throughout the body and the disease speedily proves fatal. Of late, moreover, attention has also been called to Pasteur's researches on the subject of the very fatal epidemic which raged for fifteen years amongst the silkworms of France. This affection, known by the name of perine, is dependent upon the presence and multiplication of peculiar corpuscular organisms, called Psorospermia, in all the tissues of the body. Both these general parasitic diseases are highly contagious; both are contagious by means of organisms; and in both the virus does increase by self-multiplication within the body of the animal affected. What more suggestive evidence could there be as to the truth of the "germ-theory," say its advocates, than is supplied by the phenomena of these two diseases? Undoubtedly the evidence is irrefragable as to its applicability to these particular maladies; but then comes the question whether they are comparable with the other affections to which the "germ-theory" is sought to be applied. And this question must decidedly be answered in the negative. These parasitic diseases are sharply distinguished from the others by the fact of their almost invariable fatality. Creatures or persons once affected in this way are, under ordinary circumstances, thenceforth on the road to more or less immediate death. Happily, however, no fatality of this kind is characteristic of even such highly contagious diseases as scarlet fever and smallpox, or any other of the maladies with which parasitic organisms cannot be shown to be associated. Doubtless there are other general parasitic diseases amongst animals. In almost all the specific diseases to which man is liable, however, I have invariably failed to discover any trace of organisms in the blood. The experience of many other observers has been similar to my own in this respect. But if living things were really present as causes of these maladies, then most assuredly ought they to conform to that fatal type which is almost inseparable from the notion of a general parasitic disease, and which we find exemplified by the course of pebrine, the "blood," and "malignant pustule."+ The fact then, that the general tendency in the acute specific diseases, is undoubtedly towards recovery rather than towards death, speaks strongly against the resemblance supposed to exist between them and the parasitic affections alluded to, and also against the hypothesis that they are dependent upon the presence of self-multiplying germs within the body. Such germs, when present, would be sure to go on increasing until they brought about the death of their host.

These considerations alone should suffice to inspire grave doubts as to the truth of the "germ-theory." And such doubts may be reinforced by many others. Thus, the several affections being distinct from one another, this theory demands a belief in the existence of about twenty different kinds of organisms never known in their mature condition, but whose presence as invisible, non-developing germs is constantly postulated, solely on the ground of the occurrence of certain effects supposed to be otherwise incapable of occurring. That, if existent, they are no mere ordinary germs of known organisms is obvious, because the presence of these has again and again been shown to be incapable of producing the diseases in question. Mr. Forster says,+ "There is not perhaps on the face of the earth a human creature who lives on coarser fare, or to a civilised prople more disgusting, than a Kalmuck Tartar. Raw putrid fish or the flesh of carrion-horses, oxen, and camels--is the ordinary food of the Kalmucks, and they are more active and less susceptible to the inclemency of the weather than any race of men I have ever seen. It has, moreover, been frequently demonstrated, that the organisms of ordinary putrefactions may be introduced even into the blood of man and animals without the production of any of these specific diseases. || Yet is the "Antiseptic System * NATURE, 1870, No. 36, p. 181.

See paper by Dr. Wm. Budd in British Medical Journal, 1863. 1 See Med. Chirurg. Rev., 1854, vol. xiii., where the supposed connection of diseases with processes of putrefaction is ably considered by the late Dr.

W. Alison.

§ The Bacteria which are sure to be abundant in such food cannot, therefore, be the much talked-of “disease germs." Such a diet is, of course, by no means recommended. Epidemic diseases are frequently most fatal when they once break out amongst a people whose diet is of this kind (see Dr. Carpenter, in Med, Chirurg. Rev., 1853, vol. xi. p. 173), and could probably only be borne in certain climates by persons who lead a very active life.

See, amongst others, Davaine in Compt, Rend, August 1864, and E. Semmer in Virchow's archives, 1870. Dr. Lionel Beale is well aware of this fact, and he, accordingly, whilst adhering to the germ theory, promil gates it under a new form. He says (Monthly Micros. Jour., Oct. 1870 p. 205) -"Concerning the conditions under which these germs are pro duced, and of the manner in which the rapidly multiplying matter acquires ts new and marvellous specific powers, we have much to learn, but with

of treatment (good as it may be, irrespective of the germtheory on which it has been based) pressed upon our attention on the assumption that the germs of putrefaction and the germs of disease are living organisms similar in nature. The strange persistency with which this view is advocated is not a little surprising, when it entails the obvious contradiction that germs which do, under all ordinary circumstances, develop into well-known organic forms, should, when concerned in the production of the diseases in question, induce all the effects supposed to depend upon their prodigious growth and multiplication, and yet never develop, never become visible. And, whilst Bacteria and other organisms with which the unknown disease-germs are compared, flourish and reproduce in the much-vaunted, germ-killing, carbolised lotions; still carbolic acid continues to be recommended solely on account of its germ-killing powers, and the theory on which the practice is based is thought to derive support from the results obtained by the use of this agent. Surely no theory could be weaker on which to base a successful method of treatment; and if, as its distinguished originator says, its general acceptance is principally hindered by the "doubt of its fundamental principle," then I would deliberately say that the blame, if any, cannot fairly be said to lie with those "who have opposed the germtheory of putrefaction." The " Antiseptic System" of treatment needs no support from a germ-theory; it can be surely and unassailably based upon the broader physico-chemical doctrines of Liebig.+

The last blow, however, seems given to the "germ-theory" of disease, when we are told that the blood and the secretions in sheep-pox are not infective, though this disease is most closely allied to, and even more virulently contagious than, human small-pox. If germs had existed in th's general disease, and their multiplication was the cause of it, then most assuredly would they have existed in the blood and in other fluids of the body; and yet, as Prof. Burdon Sanderson tells us, § "In sheep-pox all the diseased parts are infecting, while no result follows from the inoculation either of the blood or of any of the secretions; the liquid expressed from the pulmonary nodules has been found by M. Chauveau to be extremely virulent-certainly not less so than the juice obtained from the pustules." Now, although in other of these diseases the blood does undoubtedly exhibit infective properties, still the ascertained existence of even one exceptional case amongst maladies so contagious as sheep-pox, seems to be absolutely irreconcilable with the theory of the "germ-theory," more especially when this theory was started principally to explain the phenomena of such highly contagious diseases. ||

vegetable organisms the germs have nothing to do. They have originated in man's organism. Man himself has imposed the conditions favourable to their development. Man alone is responsible for their origin. Human intelligence, energy, and self-sacrifice may succeed in extirpating them, and may discover the means of preventing the origin of new forms not now in exisence." This is undoubtedly a very much less objectionable form of the germ theory, though much additional evidence would be needed before we could accept the view that contagious diseases are due to the rapid multiplication of the contagious particles within the body of the creature affected. The non-contagiousness of the blood is as irreconcilable with this as with the other form of the germ theory.

* See "Modes of Origin of Lowest Organisms," 1871, p. 85. And in a recently published paper "On the Relative Powers of Various Substances in Preventing the Generation of Animalcules on the Development of the Germs," Dr. Dougall says: "If, as is alleged, germs are the source of putrefaction, then the strongest preventives must be the best antiseptics, and vice versa. Now, as seen in the table, carbolic acid occupies a very mediocre place as a preventive, therefore it is legitimate to conclude that it stands no higher as an antiseptic," p. 13.

British Medical Journal, August 26, 1871, p. 225.

These doctrines do not seem to have been adequately grasped by Prof. Lister. Fragments of organic matter are believed by Liebig to be capable of acting as ferments; he, however, holds that their potency is deteriorated by heat almost as much as are the qualities of living ferments. The experiments with boiled fluids in bent-neck flasks, therefore, upon which Prof. Lister so strongly relies in proof of the germ-theory, prove absolutely nothing as between the two theories of fermentation of Liebig and of Pasteur. Amongst the atmospheric particles there are sure to be dead ferments in the form of mere organic fragments. Now the doubt that previously existed was, as to whether they could initiate fermentation and putrefaction, or whether the presence of living germs was absolutely essential. In the experiments with bent-neck flasks, both fragments and germs must be simultaneously excluded or admitted to the fluids. Prof. Lister's readers might suppose that Liebig had no objection to his ferments being boiled, and that the issue lay between the relative efficiency of oxygen and living germs. (See Gerhardt's Chimie Organique, t. iv. p. 545.)

Report" On the Intimate Pathology of Contagion," in Twelfth Report of Medical Officer of Privy Council.

Inoculation with the blood of a person suffering from measles has also in several cases failed to reproduce the disease. The different severity of small-pox taken in the ordinary way, and that induced by "inoculation the matter of a small-pox pustule, is also quite inexplicable in accordance with the "germ theory."

of

PROF. BASTIAN ON THE GERM THEORY BOOKS RECEIVED.