August 2 1, 1879] 



NATURE 



399 



be shortly, but not unjustly, described as a process of intellectual 

 "thimble-rigging," by which the unwary spectator is apt to be 

 cheated out of his most valuable mental possession — his rational 

 certainty. 



The same spirit asserts that our psychical powers never them- 

 selves enter into the circuit of physical causation, and yet few 

 things would seem more certain to a plain man than that (sup- 

 posing him to have received a message saying his house is 

 on fire) it is his knowledge of what has been communicated 

 which sets him in motion. To deny this is to deny the evident 

 teaching of our consciousness. It is to deny what is necessarily 

 the more certain in favour of what is less so. If I do not know 

 this I know nothing, and discussion is useless. As a distin- 

 guished writer has said : ' ' That we are conscious, and that our 

 actions are determined by sensations, emotions, and ideas, are 

 facts which may or may not be explained by reference to mate- 

 rial conditions, but which no material explanation can render 

 more certain." The advocate of "natural selection " may also 

 be asked. How did knowledge ever come to be, if it is in no 

 way useful, if it is utterly without action, and is but a super- 

 fluous accompaniment of physical changes which would go on 

 as well without it ? 



As we may be confident that thought not only is but also acts, 

 as well as that there are things which are not psychical, but 

 which are physical ; so I would urge that the conception of 

 livir.g things, which I venture to put before you, is one which 

 may be rationally entertained. 



Assuming for the moment and for argument's sake that it may 

 be accepted, what light does our knowledge of ourselves throw 

 upon the intimate life-processes of lower organisms ? We know 

 that with us a multitude of actions, which are at first performed 

 with coasciousness, come to be performed unconsciously ; we 

 know that we experience sensations ' w'ithout perceiving them ; 

 we know also that countless organic activities take place in us 

 under the Influence and control of the nervous system, which 

 either never rise into consciousness at all, or only do so under 

 abnormal conditions. Yet we caimot but think that those activi- 

 ties are of the same generic nature, w hether we feel, perceive, 

 or attend to them or not. The principle of individuation in 

 ourselves, then, evidently acts with intelligence in some actions, 

 with sentience in many actions, but constantly in an unperceived 

 and unfelt manner. Yet we have seen it undeniably intervene 

 in the chain of physical causation. 



An animal is an organism eU the actions of which are neces- 

 sarily determined by the adjustments of its various organs, and 

 I by its environment. But even its sensations cannot be regarded 

 I as mere accompaniments of its activities, but as guides and 

 I directing agencies intervening in the circle of its actions, and as 

 j facts, in the chain of physical causation. The sight of a stick 

 may change the course of actions which a dog would otherwise 

 have pursued — that is, the feeling of the moment, together with 

 the faint recurrence of various past feelings and emotions there- 

 with associated which the sight of the stick calls up, may cause 

 snch change. Besides its feelings, the general and the organic 

 ■movements of the dog are, like our own, governed by a mnlti- 

 tude of organic influences which are not felt, but which operate 

 through the nervous system, and so must be taken as parallel 

 with those which are felt, i.e. as unfelt, nervous psychoses. 

 The animal, then, like each of us, is a creature of activities 

 partly physical, partly psychical, the latter — both the felt and 

 the unfelt — being directive and controlling. 



As we descend to the lowest animals, the evidence as to sen- 

 tience fades. Vet from the resemblances of the lowest animals 

 and plants, and from the similarity of the vegetative functions 

 in all living creatures, we may, I think, analogically conclude 

 that activities also take place in plants which are parallel with, 

 and analogous to, the unfelt psychoses of animals. As Asa 

 Gray has said with respect to then- movements : " Although 

 these are incited by physical agents (just as analogous kinds of 

 movements are in animals), and cannot be the result of anything 

 like volition, yet nearly all of them are inexplicable on mechani- 

 cal principles. Some of them at least are spontaneous motions 



^ "a physic.1l state." Then a sensation and its physical accompaniment may 

 be represented by the symbol a -\- b. But a physical state is itself but a 

 st.ite of consciousness with its objective correlate, and is, therefore, a -^ h. 

 We thus get an equation infinitely more erroneous than ^ = a -f ^, because 

 the b of the rt -f is itself ever asain and again a -^^ b. 



' As when having gazed vacantly through a window we revert to the pages 

 of a manuscript we may be writing and see there the spectra of the window 

 bars we had before uncunsciuusly seen. Here the efiect on the organism 

 mutthave been similar to what it would have been had we attended to it— 

 'V., it was unfelt sensation. 



of the plant or organism itself, due to some inherent power 

 which is merely put in action by light, attraction, or other 

 external influences." 



I have already adverted to insectivorous plants, such as 

 Dionaa. In such plants we have susceptibilities strangely like 

 those of animals. An impression is made, and appropriate re- 

 sulting actions ensue. Moreover, these actions do not take 

 place without the occurrence of electrical changes similar to 

 those which occur in muscular contraction. Hardly less note- 

 worthy are the curious methods by which the roots of some 

 plants seek moisture as if by instinct, or those by which the ten- 

 drils of certain climbers seek and find appropriate support, and 

 having found it, cling to it by a pseudo-voluntary clasping, or, 

 finally, those by which the little " Mother-of-a-thousand " ex- 

 plores surfaces for appropriate hollows in which to deposit her 

 progeny. 



Nevertheless, nothing in the shape of vegetable nervous or 

 muscular tissue has been detected, and as structure and function 

 necessarily vary together, it is impossible to attribute sensations, 

 sense perceptions, instincts, or voluntary motions to plants, 

 though the principle of individuation in each acts as in the unfelt 

 psychoses of animals and harmonises its various life-processes. 



The conception, then, which commended itself to the clear and 

 certainly unbiassed Greek intellect of more than 2,000 years ago, 

 that there are three orders of internal organic forces, or prin- 

 ciples of individua'ion, namely, the rational, the animal, and 

 the vegetal,! appears to me to be justified by the light of the 

 science of our own day. 



I come now to the bearing of these remarks on the science of 

 biology generally. 



Animals and plants may, as I have before said, be regarded 

 either statically, by anatomy, or dynamically, by physiology. 



Physiology, as usually understood, regards the properties of 

 the ultimate morphological components of organisms, the powers 

 of the various aggregations of such components, i.e. of the 

 various "tissues" and the functions of the different special 

 aggregations and arrangements of tissues which constitute 

 ' ' organs." 



But as each living creature is a highly complex unity — both a 

 unity of body and also a unity of force, or a synthesis of activities 

 • — it seems to me that we require a distinct kind of physiology 

 to be devoted to the investigation of such syntheses of activities 

 as exist in each kind of living creature. I mean to say that just 

 as we have a physiology devoted to the several activities of the 

 several organs, which activities are the functions of those organs, 

 so we need a physiology specially directed to the 'physiology of 

 the living body considered as one whole, that is, to the power 

 which is the function, so to speak, of that whole, and of which the 

 whole body, in its totality, is the organ.'- 



In a word, we need a physiology of the individual. This 

 science, however, needs a distinct appellation. I think an 

 adequate one is not far to seek. 



Such a line of inquiry may be followed up, whatever view be 

 accepted as to the nature of those forces or activities which living 

 creatures exhibit. But if we recognise, as I myself think our 

 reason calls on us to recognise, the existence in each living being 

 of such a " principle of individuation " as I have advocated the 

 recognition of, then an inquiry into the total activity of any 

 living being, considered as one whole, is tantamount to an 



' Difficult as it confessedly is to draw the dividing line between animals 

 and plants, such difficulty is not inconsistent with the existence of a really 

 profound difference between the two groups. That there should be a radical 

 distinction of nature between two organisms, which distinction our senses 

 nevertheless, more or less fail to distinguish, is a fact which on any view 

 must be admitted, since animals of very different natures may be indistin- 

 guishable by us in the germ, and in the earlier stages of their development. 

 The truth of this is practically supported by the late Mr. Lewes, who says 

 (as to the difference between the protoplasms from which'atiim.ils and plants 

 respectively arise) ; " That critical differences must exist is proved by the 

 divergence of the products. The vegetable cell is not the animal cell ; and 

 although both plants and animals have albumen, fibrlne, and caseine, the 

 <^tfwV(z/iV« of these are unlike. Homy substance, connective tissue, nerve 

 tissue, cbitine, biliverdine . . . and a variety of other products of evolution 

 or of waste, never appear in plants ; while the hydrocarbons abundant in 

 plants are, with two or three exceptions, absent from animals. Such facts 

 imply differences in elemtJltary composition ; and this result isfurther en- 

 forced by the fact that when the two seem to resemble, they are still different. 

 The plant protoplasms form various cells, but never form a cartilage cell, or 

 a nerve cell: fibres, but never a fibre of ehistic tissue; tubes, but never a 

 nerve tube : vessels, but never a vessel with muscular coatings ; solid 

 " skeletons," but always from an organic substance (feilulose), not from 

 phosphates and carbonates. In no one character can we say that the plant 

 anl the animal are identical; we can only point throughout the two 

 kingdoms to a great similarity accompanying a > radical diversity. —"The 

 Physical Basis of Mind," p. 129. 



