the stoppers or corks being at once inserted, the vessels and their contents were set aside to cool. When the filtered infusion of hay or turnip had been rapidly cooled down to about 110° F. (by letting the beaker containing it stand in a large basin of cold water), it was inoculated with some of a turbid infusion of hay swarming with active Bacteria and Vibriones--in the proportion of one drop of the turbid fluid to each fluid ounce of the now clear filtered infusion. The beaker was then placed upon a sand-bath, and its contained fluid (in which a thermometer was immersed) gradually raised to the required temperature. The fluid was maintained at the same temperature for five minutes by alternately raising the beaker from and replacing it upon the sand-bath. The bottles to be used were then one by one uncorked, emptied, and refilled to the brim with the heated, inoculated fluid. The corks or stoppers were at once very tightly pressed down so as to leave no air between them and the surface of the fluids. The beaker was then replaced upon the sandbath and the gas turned on more fully, in order that the experimental fluid might be rapidly raised to a temperature 9° F. (5° C.) higher than it had been before. After five minutes' exposure to this temperature o'her bottles were filled in the same manner, and so on for the various temperatures the influence of which it was desired to test.

Thus prepare, the bottles and tubes have been exposed during the day to a temperature ranging from 65° to 75° F. And generally one had not to wait long in order to ascertain what the results were to be. In some cases, if the contents of the vessels were to become turbid, this was more or less manifest after an interval of forty-eight hours. In other cases, however, the turbidity manifested itself three or more days later, and the reason of this difference will be fully discussed in a sub. sequent communication.

For the sake of simplicity and brevity, the necessary particu. lars concerning the 102 experiments have been embodied in the table which will be found below.

The experimental results here tabulated seem naturally divisible into three groups. Thus, when heated only to 131° F, all the infusions became turbid within two days, just as the inoculated saline solutions had done. Heated to 158° F. all the inoculated organic infusions remained clear, as had been the case with the saline solutions in my previous experiments, when heated to 140° F. There remains, therefore, an intermediate heat zone (ranging from a little below 140° to a little below 158° F.), after an exposure to which the inoculated organic infusions are apt to become more slowly turbid, although inoculated saline solutions raised to the same temperatures invariably remain unaltered. The full explanation of these apparent anomalies I propose to make the subject of a future communication to the Royal Society; meanwhile we may quite safely conclude that Bacteria, Vibriones, and their supposed germs are either actually killed or else completely deprived of their powers of multiplication after a brief exposure to the tem perature of 158° F. (70° C.).

takes place and the fluids thus situated rapidly become turbid. There is therefore nothing in the conditions themselves tending to hinder the process of putrefaction, so long as living units are there to initiate it. Our experiments now show that as long as the added Bacteria, Vibriones, and there supposed germs are subjected to a heat not exceeding 131° F. (55° C.), putrefaction invariably occurs within two days, whilst, on the contrary, whenever they are subjected to a temperature of 158° F. (70° C.) putrefaction does not occur. To what can this difference be due, except to the fact that the previously living organisms which, when living, always excite putrefaction, have been killed by the temperature of 158° F.? It would be of no avail to suppose that the absence of putrefaction in these latter cases is due to the fact that a heat of 158° F., instead of killing the organisms and their germs, merely annuls their powers of reproduction, because in the other series of experiments (with which these have to be compared) where similar fluids are exposed to ordinary or purified air, or are shut off from the influence of air altogether, the most active putrefaction and multiplication of organisms takes place in two, three, or four days, in spite of the much more potent heat of 212° F., to which any pre-existing germs or organisms must have been subjected. The supposition, therefore, that the Bacteria, Vibriones, and their germs were not killed in our inoculation experiments at the temperature of 158° F., but were merely deprived of their powers of reproduction, would be no gain to those who desire to stave off the admission that Bacteria and Vibrones can be proved to arise de novo in certain cases. Let us assume this-which is indisputably proved by these inoculation experiments-viz. that an exposure to a temperature of 158° F. (70° C.) for five minutes deprives Bacteria, Vibriones, and their germs of their usual powers of growth and reproduction-that is that it reduces them to a state of potential, if not necessarily to one of actual death. What end would be served by such a reservation? The impending conclusion would not be staved off by means of it. The explanation of what occurs in the other set of experiments, where the much more potent heat of 212° F. is employed, still would not be possible without having recourse to the supposition of a de novo origination of living units, so long as those which may have pre-existed in the flask could be proved to have been reduced to such a state of potential death. It would be preposterous, and contrary to the whole order of nature, to assume that the vastly increased destructive influence of a heat of 212° F. had restored vital properties which a lesser amount (158° F.) of the same influence had completely annulled.

The evidence supplied by these different series of experiments in whichever way it is regarded, as it seems to me, absolutely compels the logical reasoner to conclude that the swarms of living organisms which so often make their appearance in boiled infusions treated in one or other of the various modes already proved to be either destructive or exclusive of pre-existing living things, are the products of a new brood of "living particles, which, in the absence of any co-existing living organisms, must have taken origin in the fluid itself. For this mode of origin of living units, so long spoken of and repudiated as spontaneous generation," I have proposed the new term Archebiosis. Inoculation Experiments made with the view of ascertaining the Temperatures at which Bacteria, Vibriones, and their Supposed Germs are killed in Organic Infusions.

66

Thus, we now know that boiled turnip- or hay-infusions exposed to ordinary air, exposed to filtered air, to calcined air, or shut off altogether from contact with air, are more or less prone to swarm with Bacteria and Vibriones, in the course of from two to six days. But, placed under slightly different conditions such as were employed in the inoculation experiments above quoted, although infusions of the same nature do not undergo spontaneous" putrefactive changes, yet when living Bacteria and Vibriones are added and not subsequently heated, putrefaction invariably tightly fitting corks; and the latter And have answered quite as well as the former On the whole I have ound tightly corked 1 oz. phials to be about the most convenient vessels to employ in these inoculation experiments.

It was found desirable to filter the infusions after they had been boiled, because the boiling generally somewhat impaired their clearness.

At this stage, of course, very great care is needed in order to avoid all chance of accidental contamination either with living organisms or with tinheated fragments or particles of organic matter.

NEUTRAL HAY INFUSION.

exposed. periments made.

122° F. (50°C.) 131°F.

if any.

tion of the 8th day.

1 In the experiments already referred to.

TH

THURSDAY, APRIL 10, 1873

INSTINCT

HE very valuable contribution to Psychology made by Mr. Spalding in his paper on Instinct (Macmillan's Magazine for February), and the letters and article which have lately appeared in this Journal, will no doubt stimulate research, and lead to some rational explanation of what has hitherto been enveloped in a mist of metaphysics. Mr. Spalding has not only proved himself an acute thinker, he has shown a rare ability in devising experiments, and we may fairly expect that his researches will mark an epoch. I am the more grateful to him because his instructive results, though seeming to contradict, do really furnish experimental confirmation of the views put forth in my work, now in the press, wherein it is argued that Instinct is lapsed Intelligence: that what is now the fixed and fatal action of the organism, was formerly a tentative and discriminating (consequently intelligent) action in a word that what is now a connate tendency was formerly acquired experience.

There is great need of precise definition of terms. What is Instinct? What is Experience? What is Intelligence? Twenty different writers indicate twenty different things by these terms. They do not distinguish between Instinct and Impulse; between Experience acquired by the individual, and Experience transmitted from ancestors; between Intelligence, the discernment of Likeness and Unlikeness in feelings, and Intellect, the discernment of Likeness and Unlikeness in symbols. Above all they seldom make clear whether they are treating any fact from the psychological or from the psychogenetical point of view, i.e. whether they are describing the Anatomy or the Morphology of the Mind. It is, for instance, one thing to affirm that our perception of Space is a perception necessarily conditioned by our organism, and in that sense à priori; another thing to affirm that this conditioned structure is itself the evolved result of ancestral experiences of Sight, Touch, and Motion, and in that sense the perception of space is à posteriori. The point of difference between the empirical and nativistic❘ schools may be got rid of by such a precision in the question. The vital point will then be between the advocates of evolution and the advocates of creation. Those who hold that the Organism is evolved, must hold that its perceptions (and instincts) are evolved through Experience. Those who hold that the Organism is created, and was from the first what we see it now, must hold that its perceptions (and instincts) are pre-ordained, and have no experiential origin whatever.

Having thus cleared the ground of a mass of obstruction, we may now approach the subject of Instinct. In what sense can it be said to be dependent on Experience? Obviously this cannot be answered till we are agreed on the meaning to be assigned to the term Experience. I have defined it the registration of Feeling. And what is Feeling? It is reaction of the sentient Organism under stimulus. This reaction has obviously two factors: the structure of the organism, and the nature of the stimulus. It is not every response of the organ that can be a feeling, it is not every feeling that can be an experience. The No. 180-VOL. VII.

secretion of a gland is a response, physiologically similar to the response of a sensory organ; but the former is not a feeling, although it enters as an element into the mass of Systemic sensation; and the response of a sensory organ, although a feeling, will not be an experience unless it be revivable; and this revival requires that it should be registered in the modification impressed on the sentient structure. It is true that rigorously speaking no body, not even an inorganic body, can be acted on without being modified; every sunbeam that beats against the wall alters the structure of that wall; but these minute alterations are not only inappreciable for the most part, by any means in our power, they are also mostly annulled by subsequent alterations. In one sense, therefore, no impression ever excites Feeling without modifying the sentient structure; but some impressions, especially when iterated, produce definite and permanent modifications; and these are registrations capable of revival, i.e. of the feelings registered, so that when the organism is stimulated its reaction will be determined by those past reactions, and the product will be a feeling more or less resembling the feelings which were formerly produced. Thus we have Feeling as the reaction of the Organism; and the Organism itself as a structure which has been modified by its reactions on external stimuli. What the structure of the Organism is at any stage determines what will be the kind of sentient reactions it will have. Experience is the registration of Feeling, registered in those modifications, which, because they are modifications of structure, must have corresponding activities of Feeling, and from these spring Actions. To trace the history of these modifications or their feelings is Morphology or Psychogeny; to describe their results is Anatomy or Psychology.

We cannot be in doubt then whether Instinct is or is not dependent on Experience; we can only ask: Is a particular action characteristic of a particular animal species, one that the animal has itself learned to perform through the adaptation of its organs, under the guidance of sensible impressions reviving the past impressions of its experience; or an action inevitably determined by the reactions of the structure inherited from ancestors, so that sensible impressions revive ancestral experiences registered in the modifications impressed on the structure? The answer in each case can only be approximative; and for this reason: until the organism has the requisite degree of development for the performance of the actions, there can be no manifestation of the instincts, and there are few of the instincts manifested at birth.

How, then, shall we define Instinct? How separate the actions which are congenitally determined, from those which are incidentally determined? Both require the indispensable conditions of an appropriate structure and appropriate stimuli. It is obvious that we cannot fix upon the structure alone; and yet the congenital tendencies of that structure must be taken into account; for we see instincts not manifested until long after many other actions have been acquired-as in the case of the sexual instinct. But if congenital tendencies sufficed, we should call the flowering of plants at their normal season when transplanted to a different climate, an instinct. Many would say that an action common to an entire

BB

group of animals must be an instinct, since it could not be acquired through individual experience. But how if the conditions of acquisition are also common to the whole group? Thus an infant certainly learns to scratch itself; since, however it may itch, some considerable experience is necessary before it learns to localise the sensation. As, however, the conditions of this acquisition are common to all children, all learn to scratch themselves. Now in many animals this is an inherited acquisition; they scratch themselves from the first. Whether the infant also inherits a structure which would develop into one as apt as that of the animal, cannot be ascertained; all we know is that the infant's nervous structure is too immature at first to permit the localisation of sensation. How much of the subsequent aptitude is the result of congenital tendency, and how much of acquisition through incidental experiences acting on a predisposed organism, cannot be estimated.*

That we require some character to distinguish the instinctive from the impulsive actions, may be readily shown. No one calls Breathing, Secretion, Excretion, &c., instincts. Yet these are the actions of congenital tendencies in the organism. "A hungry chick," says Mr. Spalding, "that never tasted food, is able on seeing a fly or spider for the first time, to bring into action muscles that never were so exercised before, and to perform a series of delicately adjusted movements that end in the capture of the insect." Every one would pronounce this a typical case of Instinct. Now compare with it the following, which no one would class among the instincts: A newborn animal that has never breathed before is able on first feeling the stimulus of the atmosphere to bring into action a very complicated group of muscles which never were so exercised before, and to perform a series of delicately adjusted movements which end in the aëration and circuculation of the blood.

This contrast may lead us to the character sought. Understanding that every line of demarcation in psychical phenomena must be more or less arbitrary, and only justified by its convenience, we may draw such a line between Impulse and Instinct. Impulses are the actions which from the first were fatal, inevitable, being simply the direct reflex of the stimulated organs. Given the respiratory organs and the atmosphere, Respiration is the inevitable result. Given the secretory organ and the plasma, Secretion is the inevitable result. There is no choice, the action either takes place or it does not.

Instincts are also fatal, inevitable, but they were not always so; the element of choice intervenes; and although the intelligent discrimination may be almost entirely lapsed, it never is wholly lapsed. The guiding sensation is still discriminative, selective. Hence instincts vary with varying conditions. Thus the nutritive impulse which when unsatisfied causes the uneasiness of desire, and which moves the animal in search of food, is markedly distinguishable from the instinct which selects the appropriate food and rejects all the rest. If an animal eats only certain kinds of food, out of many which would be nutritious, it is because these kinds have been selected by it, or by its ancestors. Every chicken, Mr. Spalding assures

The examples of dogs and horses finding their way home, however marvellous, cannot be affiliated on Instinct, since it is very far from common to the species: for one dog who finds his way home, hundreds are helpess when lost.

us, has to learn not to eat its own excrement. "They made this mistake invariably, but they did not repeat it oftener than once or twice." He also has this remark :Chickens, as soon as they are able to walk, will follow any moving object; and when guided by sight alone they seem to have no more disposition to follow a hen than to follow a duck or a human being. Unreflecting onlookers when they saw chickens a day old running after me, and older ones following me miles and answering my whistle, imagined that I must have some occult power over the creatures, whereas I simply allowed them to follow me from the first. There is the instinct to follow; and, as we have seen, their ear, prior to experience, attaches them to the right object."

I should rather say, "there is the impulse to follow: and the instinct to follow the mother, or a duck, or the master who feeds them, is the selected action which becomes rapidly an organised habit." It is one of the conclusions of my work that all our involuntary and automatic actions, were originally voluntary, and that all In the instinctive actions were originally intelligent. case now under consideration, the impulse to follow is a fixed tendency; the instinct to follow is facultative at first, and becomes fixed by habit, but is always, even when most firmly fixed, guided by discriminating feeling.

To conclude: where there is no alternative open to an action it is impulsive; where there is, or originally was, an alternative, the action is instinctive; where there are alternatives which may still determine the action, and the choice is free, we call the action intelligent.

GEORGE HENRY LEWES

HANDBOOK FOR THE PHYSIOLOGICAL LABORATORY

Handbook for the Physiological Laboratory. By E. Klein, M.D.; J. B. Sanderson, F.R.S.; M. Foster, F.R.S.; and T. L. Brunton, M.D., D.Sc. (Churchill.)

TUDENTS of chemistry have, for a long time, by

the opportunity, almost unaided, of verifying for themselves most of the experimental results of which they hear in lectures, and read in text-books; and thus many are able, before they have finished their educational course, to obtain a thorough practical knowledge of the science. Such has not been the case with regard to physiology; the subject is less advanced, and has progressed more slowly; perhaps this is because the descriptions of the methods by which the ends have been arrived at, as given by lecturers and writers, are incomplete and insufficient. The work before us is the first important attempt that has been made to put the commencing physiologist in a fair position to begin original work on the subject, by giving him the necessary directions for himself performing many of the fundamental experiments on which the science is based. Whether physiology in its most comprehensive sense, as understood by the authors of this work in their title, is a single branch of science which can be thus treated in its unity, or whether it ought to be divided up and incorporated with others already established, is a point which has not yet been satisfactorily settled, and which the perusal of this book may assist in proving.