424 



NA TURE 



[September 3, 1908 



space at my command does not permit me to give a full 

 account of his interesting speculation on somatic inherit- 

 ance. It resembles the theories of Hering, Butler, and 

 Semon in postulating a quality of living things, which is 

 the basis both of memory and inheritance. But it differs 

 from them in seeking for a physical explanation or model 

 of what is common to the two. He compares the nucleus 

 to an electric accumulator which in its discharge gives 

 out the same sort of energy that it has received. How 

 far this is an allowable parallel 1 am not prepared to say, 

 and in what follows I have given Rignano's results _ in 

 biological terms. What interests me is the conclusion 

 that the impulse conveyed to the nucleus of the germ-cell 

 is, as far as results are concerned, the external stimulus. 

 Thus, if a somatic cell (A) is induced by an external 

 stimulus (S) acting on the nucleus to assume a new manner 

 of development, a disturbance spreads through the 

 organism, so that finally the nuclei of the germ-cells are 

 altered in a similar manner. When the cellular descendants 

 of the germ-cells reach the same stage of ontogeny as that 

 in which the original stimulation occurred, a stimulus 

 comes into action equivalent to S as regards the results 

 it is capable of producing. So that the change originally 

 wrought in cell A by the actual stimulus S is now repro- 

 duced by what may be called an inherited stimulus. But 

 when A was originally affected other cells, B, C, D, may 

 have reacted to S by various forms of growth. And 

 therefore when during the development of the altered germ- 

 cell something equivalent to S comes into play, there will 

 be induced, not merely the original change in the develop- 

 ment of A, but also the changes which were originally 

 induced in the growth of B, C, D. Thus, according to 

 Rignano, the germ-nucleus releases a number of develop- 

 mental processes, each of which would, according to 

 Weismann, require a separate determinant. 



If the view here given is accepted, we must take a new 

 view of Weismann's cases of simultaneous stimtilation, i.e., 

 cases like Fischer's experiments on Arctia caja, which he 

 does not allow to be somatic inheritance. If we are right 

 in saying that, the original excitation of the soma is trans- 

 ferred to the germ-cell, and it does not matter whether 

 the stimulus is transferred by "telegraphy," or whether 

 a given cause, e.g., a low temperature, acts simultaneously 

 on soma and germ-cell. In both cases we have a given 

 alteration produced in the nuclei of the soma and the 

 germ-cell. Nageli used the word telegraphy to mean a 

 dynamic form of transference, but he did not exclude the 

 possibility of the same effect being produced by the move- 

 ment of chemical substances, and went so far as to suggest 

 that the sieve tubes might convey such stimuli in plants. 

 In any case this point of view ' deserves careful considera- 

 tion. 



Still another code of communication seems to me to be 

 at least conceivable. One of the most obvious character- 

 istics of animal life is the guidance of the organism by 

 certain groups of stimuli, producing either a movement 

 of seeking (positive reaction ") or one of avoidance (negative 

 reaction). Taking the latter as being the simplest, we 

 find that in the lowest as in the highest organisms a given 

 reaction follows each one of a number of diverse conditions 

 which have nothing in common save that they are broadly 

 harmful in character. We withdraw our hands from a 

 heated body, a prick, a corrosive substance, or an electric 

 shock. The interesting point is that it is left to the 

 organism to discover by the method of trial and error the 

 best means of dealing with a sub-injurious stimulus. May 

 we not therefore say that the existence of pleasure and 

 pain simplifies inheritance? It certainly renders unneces- 

 sary a great deal of detailed inheritance. The innumer- 

 able appropriate movements performed by animals are 

 broadly the same as those of their parents, but they are 

 not necessarily inherited in every detail ; they are rather 

 the unavoidable outcome of hereditary but unspecialised 

 sensitiveness. It is as though heredity were arranged on 

 a code-system instead of by separate signals for every 

 movement of the organism. 



It may be said that in individual life the penalty of 

 failure is pain, but that the penalty for failure in onto- 



See Semon, Archkif. Rasscn. und Gt'selhchafts-Bwlogk, 1907, p. 39. 

 See Jennings, " Behaviour of the Lower Organisms." 



NO. 2027, VOL. 78] 



genetic morphology is death. But it is only because pain 

 is the shadow cast by Death as he approaches that it is 

 of value to the organism. Death would be still the penalty 

 of creatures that had not acquired this sensitiveness to 

 the edge of danger. Is it not possible that the sensitive- 

 ness to external agencies by which structural ontogeny is 

 undoubtedly guided may have a similar quality, and that 

 morphological variations may also be reactions to the edge 

 of danger. But this is a point of view I cannot now 

 enter upon. 



It may be objected that the inheritance of anything so 

 complex as an instinct is difficult to conceive on the 

 mnemic theory. Yet it is impossible to avoid suspecting 

 that at least some instincts originate in individual acquire- 

 ments, since they are continuous with habits gained in the 

 lifetime of the organism. Thus the tendency to peck at 

 any small object is undoubtedly inherited ; the power of 

 distinguishing suitable from unsuitable objects is gained 

 by experience. It may be said that the engrams con- 

 cerned in the pecking instinct cannot conceivably be trans- 

 ferred from the central nervous system to the nucleus of ' 

 the germ-cells. To this I might answer that this is not 

 more inconceivable than Weismann's assumption that the 

 germ-cell chances to be so altered that the young chicken 

 pecks instinctively. Let us consider another case of what 

 appears to be an hereditary movement. Take, for instance, 

 the case of a young dog, who in fighting bites his own 

 lips. The pain thus produced will induce him to tuck up 

 his lips out of harm's way. This protective movement 

 will become firmly associated with, not only the act of 

 fighting, but with the remembrance of it, and will show 

 itself in the familiar snarl of the angry dog. This move- 

 ment is now, I presume, hereditary in dogs, and is so 

 strongly inherited by ourselves (from simian ancestors) that 

 a lifting of the corner of the upper lip is a recognised 

 signal of adverse feeling. Is it really conceivable that the 

 original snarl is due to that unspecialised stimulus we call 

 pain, whereas the inherited snarl is due to fortuitous upsets 

 of the determinants in the germ-cell? 



I am well aware that many other objections may be 

 advanced against the views I advocate. To take a single 

 instance, there are many cases where we should expect 

 somatic inheritance, but where we look in vain for it. 

 This difficulty, and others equally important, must for the 

 present be passed over. Nor shall I say anything more 

 as to the possible means of communication between the 

 soma and the germ-cells. To me it seems conceivable that 

 some such telegraphy is possible. But I shall hardly 

 wonder if a majority of my hearers decide that the avail- 

 able evidence in its favour is both weak and fantastic. 

 Nor can I wonder that, apart from the problem of 

 mechanism, the existence of somatic inheijitance is denied 

 for want of evidence. But I must once more insist that, 

 according to the mnemic hypothesis, somatic inheritance 

 lies at the root of all evolution. Life is a gigantic experi- 

 ment which the opposing schools interpret in opposite 

 ways. I hope that in this dispute both sides will seek 

 out and welcome decisive results. My own conviction in 

 favour of somatic inheritance rests primarily on the auto- 

 matic element in ontogeny. It seems to me certain that 

 in development we have an actual instance of habit. If 

 this is so, somatic inheritance must be a vera causa. Nor 

 does it seem impossible that memory should rule the 

 plasmic link which connects successive generations — the 

 true miracle of the camel passing through the eye of a 

 needle — since, as I have tried to show, the reactions of 

 living things to their surroundings exhibit in the plainest 

 way the universal presence of a mnemic factor. 



We may fix our eyes on phylogeny and regard the living 

 world as a great chain of forms, each of which has learned 

 something of which its predecessors were ignorant ; or 

 we may attend rather to ontogeny, where the lessons 

 learned become in part automatic. But we must remember 

 that the distinction between phylogeny and ontogeny is 

 an artificial one, and that routine and acquisition are 

 blended in life.' 



1 This subject is dealt with in a very interestine manner in Prof. Jarnes 

 Ward's forthcoming lectures on the " Realm of Ends." Also in his article 

 on "Mechanism and Morals" in the Hibhcrt Jc^m-nal, October. 1505 

 p. 92 ; and in his article on " Psychology " in the " Encyclopaedia Britan- 

 nica," 188^, vol. XX. p. 44. 



