DENIALS OF INHERITANCE 25 



adjustments or of similar permanent adaptations to the same 

 set of circumstances, though they remain, of course, internally 

 and intrinsically different. Thus we know that a worm-like 

 form of body is exhibited as an adaptive feature by many 

 vertebrates which are otherwise very unlike and very remotely 

 related. We have only to think of the hag {Myxine), the eel 

 (Anguilla), the amphibian Caecilians, the lacertilian Anguidae, 

 and the Typhlopid snakes, which illustrate this fact of homoplasty 

 or convergence. On the other hand, organisms of the same 

 species may in different surroundings exhibit, temporarily, a 

 different mode of development and growth, and a different 

 external appearance — the phenomenon of " poecilogony." 



2. Beneath the misunderstanding which has led some to deny 

 the facts of inheritance there is, as we have seen, a reasonable 

 though exaggerated recognition of the potency of similar function 

 and environment in producing resemblance ; and there is, perhaps, 

 the recognition of another fact — that of variation. For several 

 reasons — for instance, because the new life usually springs from 

 a fertilised ovum which combines maternal and paternal con- 

 tributions — the child is never quite like its parents. In other 

 words, we suppose that the germinal material from which a 

 child develops is not quite the same as that from which the parents 

 developed, or not quite the same as that from which its brothers 

 and sisters developed, and the result is variation in the true 

 sense. Each offspring has its individuality and is a new creation. 

 Even within a family it is sometimes noteworthy that no two 

 are alike, especially to the careful parent's eye, though the more 

 impartial onlooker may detect certain deep-lying features in 

 which all are alike. On the one hand, " Alle Gestalten sind 

 dhnlich " ; on the other hand, " Keine gleichet der andern." 

 But, however fully and clearly we recognise that hereditary 

 resemblance is seldom complete, we find no warrant in this for 

 a denial of the broad facts of inheritance. 



