Septembeb 25, 1908] 



SCIENCE 



395 



penalty for failure in ontogenetic mor- 

 phology is death. But it is only because 

 pain is the shadow east by Death as he ap- 

 proaches that it is of value to the organ- 

 ism. Death would be still the penalty of 

 creatures that had not acquired this sen- 

 sitiveness to the edge of danger. Is it not 

 possible that the sensitiveness to external 

 agencies by which structural ontogeny is 

 undoubtedly guided may have a similar 

 quality, and the morphological variations 

 may also be reactions to the edge of 

 danger. But this is a point of view I can 

 not 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 acquirements, since they are 

 continuous with habits gained in the life- 

 time 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 concerned in the pecking instinct 

 can not conceivably be transferred 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 con- 

 sider another case of what appears to be 

 an hereditary movement. Take, for in- 

 stance, 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 movement is now, I presume, hered- 

 itary in dogs, and is so strongly inherited 



by ourselves (from simian ancestors) that 

 a lifting of the corner of the upper lip is a 

 recognized signal of adverse feeling. Is 

 it really conceivable that the original 

 snarl is due to that unspecialized stimulus 

 we call pain, whereas the inherited snarl 

 is due to fortuitous upsets of the deter- 

 minants in the germ-cell? 



I am well aware that many other objec- 

 tions may be advanced against the views I 

 advocate. To take a single instance, 

 there are many cases where we should ex- 

 pect 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 available evidence 

 in its favor is both weak and fantastic. 

 Nor can I wonder that, apart from the 

 problem of mechanism, the existence of 

 somatic inheritance 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 experiment 

 which the opposing schools interpret in 

 opposite ways. I hope that in this dispute 

 both sides will seek out and welcome de- 

 cisive results. My own conviction in 

 favor of somatic inheritance rests primar- 

 ily on the automatic 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 ex- 



