70 



FACTS AND FANCIES 





be stated, however, that many eminent natural- 

 ists dissent from this view, and maintain that 

 even in the earliest stages material differences 

 can be observed. In this they are probably right, 

 as even Haeckel has to admit some degree of 

 divergence from this all-embracing " gastrsea " 

 theory. Admitting, however, that such early 

 similarity exists within certain limits, we find 

 that, as the embryo advances, it speedily begins 

 to indicate whether it is to be a coral-animal, a 

 snail, a worm, or a fish. Consequently, the 

 physiologist who wishes to trace the resem- 

 blances leading to mammals and to man has to 

 lop off one by one the several branches which 

 lead in other directions, and to follow that which 

 conducts by the most direct course to the type 

 which he has in view. In^ this way Haeckel can 

 show that the embryo Homo sapiens is in succes- 

 sive stages so like to the young of the fish, the 

 reptile, the bird, and the ordinary quadruped 

 that he can produce for comparison figures 

 In which the cursory observer can detect scarce- 

 ly any difference. 



All this has long been known, and has been 

 regarded as a wonderful evidence of the ho- 

 mology or unity of plan which pervades nature, 

 and as constituting man the archetype of the 



