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Part I I I. —Eighteenth Annual Report 



characters or variations are "those which are caused by the direct action 

 of external conditions." Theoretically, the difference seems obvious, yet, 

 when it comes to the working out in details, Sedgwick's own words show 

 that the distinction breaks down. In one place (p. 8) he says " it would 

 appear, then, that every feature which successively appears in an organism 

 in the march from the uninucleated zygote to death is an acquired 

 character." If so, how should we be able to tell that any observed change 

 in habit, constitution, form, or structure was genetic? 



This point is of the utmost importance in many ways, and the crux of 

 Sedgwick's position is found when we take the environment into 

 consideration. If we could conceive of a zygote developing into an adult 

 or passing through any stage whatsoever independent of the environment — 

 i.e., " outside of " an environment — then we should unhesitatingly call its 

 features " genetic." But do any features arise independent of external 

 stimuli ? So long as we are forced to believe that an organism is in touch 

 with the environment from beginning to end, then, according to his 

 own definition, we are obliged to call every feature or variation "acquired." 

 The difficulty arises from the new meaning which Sedgwick has given to 

 the words "acquired characters." Formerly these meant simply such 

 changes as were directly traceable to some impression of the environment, 

 such as mutilations, and to such as were caused by the activity of the 

 organism, such as the increase of muscular tissue. The old meaning was, 

 however, too indefinite and vague, and Sedgwick's definition undoubtedly 

 clears the air. If we accept his definition of "acquired character" as 

 given above, it is evident that we now require a new classification of 

 acquired characters. 



On this view therefore we may call the observed particular features of 

 any organ or structure an "acquired character," and the advantage of this 

 is that our attention is directed to the environmental conditions — i.e., the 

 stimuli which have led to the appearance of this particular feature. 

 Behind these characters is the formative protoplasm which tends to take 

 definite shape in diverse ways — i.e., possesses " variability " — and is finally 

 led into one particular line by particular stimuli of the environment. 



We may briefly refer also to the complex question of heredity. If all 

 the particular features of structure and form of an organism are acquired 

 in its own individual life-time, what does it receive by inheritance? 

 Obviously, as Sedgwick points out, we may conclude from the above 

 reasoning that the offspring does not receive through the germ any 

 particular feature whatsoever — i.e., acquired characters are not inherited. 

 If the same features recur in successive generations we should look for 

 the reason in the continuation or successive reappearance of similar 

 environmental stimuli. The importance of this conclusion is widespread, 

 for we account for the appearance and reappearance of particular features 

 in parent and offspring, not merely by the continuity of the germplasms, 

 but also by the continuity of the environmental conditions. In other 

 words, the so-called inheritance that parents bestow upon their offspring is 

 the inheritance of better, worse, or similar living conditions to those they 

 themselves possessed. 



It follows from these conceptions that when we talk of particular 

 characters being "preserved by inheritance" we mean that the environ- 

 mental conditions must remain the same. Thus, if we should find that a 

 particular species of fish, say, the herring or the plaice, was divisible into 

 groups, and we should say that the essential condition for the permanence 

 of each group was the continual inheritance of the parental characteristics, 

 we mean that the environmental conditions must remain similar or 

 nearly so throughout. If we had reason to believe that these conditions 

 altered, or that the parents, through migration or otherwise, did not 



