those of bilateral and vertical symmetry. Also, as the atoms of a resonant body may be made to give out sound by the juxtaposition of a vibrating tuning-fork, so it is conceivable that the physiological units of a living organism may be so influenced by surrounding conditions (organic and other) that the accumulation of these conditions may upset the previous rhythm of such units, producing modifications in thema fresh chord in the harmony of nature-a new species!

But it may be again objected, that to say that species arise by the help of an innate power possessed by organisms is no explanation, but is a reproduction of the absurdity, l'opium endormit parcequ'il a une vertu soporifique. It is contended, however, that this objection does not apply, even if it be conceded that there is that force in Molière's ridicule which is generally attributed to it.1 Much, however, might be said in opposition to more than one of that brilliant dramatist's smart philosophical epigrams, just as to the theological ones of Voltaire, or to the biological one of that other Frenchman who for a time discredited a cranial skeletal theory by the phrase "Vertèbre pensante." 2

In fact, however, it is a real explanation of how a man lives, to say that he lives independently on his own income,

1 If any one were to contend that beside the opium there existed a real distinct objective entity, "its soporific virtue," he would be open to ridicule indeed. But the constitution of our minds is such that we cannot but distinguish ideally a thing from its even essential attributes and qualities. The joke is sufficiently amusing, however, regarded as the solemn enunciation of a truism.

2 Noticed by Professor Owen in his "Archetype," p. 76. Recently it has been attempted to discredit Darwinism in France by speaking of it as "de la science mousseuse!"

instead of being supported by his relatives and friends. In the same way, there is fully as real a distinction between the production of new specific manifestations entirely ab externo, and the production of the same through an innate force and tendency, the determination of which into action is occasioned by external circumstances.

To say that organisme possess this innate power, and that by it new species are from time to time produced, is by no means a mere assertion that they are produced, and in an unknown mode. It is the negation of that view which deems external forces alone sufficient, and is at the same time the assertion of something positive, to be arrived at by the process of elimination.

All physical explanations result ultimately in such conceptions of innate power, or else in that of will force. The far-famed explanation of the celestial motions ends in the conception that every particle of matter has the innate power of attracting every other particle directly as the mass, and inversely as the square of the distance.

We are logically driven to this positive conception, if we do not accept the view that there is no force but volition, and that all phenomena whatever are the immediate results of the action of intelligent and self-conscious will.

We have seen that the notion of sudden changes-saltatory actions in nature--has received countenance from Professor Huxley.1 We must conceive that these jumps are orderly, and according to law, inasmuch as the whole cosmos is such. Such orderly evolution harmonizes with a teleology derived, not indeed from external nature directly, but from the mind of man. On this point, however, more will be said in the next chapter.

1 "Lay Sermons," p. 342.

Again, if new species have not been manifested by the action of external conditions upon minute indefinite individual differences, in what precise way may we conceive that manifestation to have taken place?

Are new species now evolving, as they have been from time to time evolved? If so, in what way and by what conceivable means?

In the first place, they must be produced by natural action in pre-existing material, or by supernatural action. For reasons to be given in the next chapter, the second hypothesis need not be considered.

If, then, new species are and have been evolved from pre-existing material, must that material have been organic or inorganic?

As before said, additional arguments have lately been brought forward to show that individual organisms do arise from a basis of in-organic material only. As, however, this at the most appears to be the case exclusively, if at all, with the lowest and most minute organisms, the process cannot be observed, though it may perhaps be fairly inferred.

We may therefore, if for no other reason, dismiss the notion that highly organized animals and plants can be suddenly or gradually built up by any combination of physical forces and natural powers acting externally and internally upon and in merely inorganic material as a

base.

But the question is, how have the highest kinds of animals and plants arisen? It seems impossible that they can have appeared otherwise than by the agency of antecedent organisms not greatly different from them.

A multitude of facts, ever increasing in number and

importance, all point to such a mode of specific manifestation.

One very good illustration has been adduced by Professor Flower in the introductory lecture of his first Hunterian Course. It is the reduction in size, to a greater or less degree, of the second and third digits of the foot in Australian marsupials, and this, notwithstanding the very different form and function of the foot in different groups of those animals.

A similarly significant evidence of relationship is afforded by processes of the zygomatic region of the skull in certain edentates existing and extinct.

Again, the relation between existing and recent faunas of the different regions of the world, and the fact that the progress in organization has been for the most part from the more general to the more special, tend to support the doctrine of evolution.

Almost all the facts brought forward by the patient industry of Mr. Darwin in support of his theory of "Natural Selection" are of course available as evidence in favour of the agency of pre-existing and similar animals in specific evolution.

Now the new forms must be produced by changes taking place in organisms at, after, or before their birth, either in their embryonic or towards or in their adult condition.

Examples of strange births are sufficiently numerous, and they may arise either from direct embryonic modifica tions or apparently from some obscure change in the parental action. To the former category belong the hosts of instances of malformation through arrest of develop

1 Introductory Lecture of February 14, 1870, pp. 24—30, Figs. 1—4. (Churchill and Sons.)

ment, and perhaps generally monstrosities of some sort are the result of such affections of the embryo. To the second category belong cases of hybridism, of cross breed, and in all probability the new varieties and forms, such as the memorable one of the black-shouldered peacock. In these cases we do not have abortions or monstrosities, but more or less harmonious forms often of great functional activity, endowed with marked viability and generative prepotency,1 except in the case of hybrids, when we often find even a more marked generative impotency.

3

It seems probable therefore that new species may arise from some constitutional affection of parental forms—an affection mainly, if not exclusively, of their generative system. Mr. Darwin has carefully collected 2 numerous instances to show how excessively sensitive to various influences this system is. He says: "Sterility is independent of general health, and is often accompanied by excess of size, or great luxuriance," and "No one can tell, till he tries, whether any particular animal will breed under confinement, or any exotic plant seed freely under culture." Again, "When a new character arises, whatever its nature may be, it generally tends to be inherited, at least in a temporary and sometimes in a most persistent manner." "4 Yet the obscure action of conditions will alter

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1 In the "Descent of Man," vol. i. p. 223, the following passage occurs: When any character has suddenly appeared in a race or species as the result of a single act of variation "and this race is crossed with another not thus characterised, the characters in question do not commonly appear in a blended condition in the young, but are transmitted to them either perfectly developed or not at all.”

2 See especially "Animals and Plants under Domestication," vol. ii. chap. xviii.

3 "Origin of Species," 5th edition, pp. 323, 324.

4"Animals and Plants under Domestication," vol. ii. p. 2.