214 THE DESCENT OF MAN 



position of the nervous system, and in possessing a structure 

 closely like the chorda dorsalis of vertebrate animals; and in 

 this he has been since confirmed by Prof. Kupffer. M. Kov- 

 alevsky writes to me from Naples, that he has now carried 

 these observations yet further; and, should his results be 

 well established, the whole will form a discovery of the very 

 greatest value. Thus, if we may rely on embryology, ever 

 the safest guide in classification, it seems that we have at 

 last gained a clew to the source whence the Vertebrata were 

 derived." We should then be justified in believing that 

 at an extremely remote period a group of animals existed, 

 resembling in many respects the larvse of our present As- 

 cidians, which diverged into two great branches — the one 

 retrograding in development and producing the present 

 class of Ascidians, the other rising to the crown and 

 summit of the animal kingdom by giving birth to the 

 Vertebrata. 



"We have thus far endeavored rudely to trace the gene- 

 alogy of the Vertebrata by the aid of their mutual affinities. 

 "We will now look to man as he exists; and we shall, I 

 think, be able partially to restore the structure of our early 

 progenitors, during successive periods, but not in due order 

 of time. This can be effected by means of the rudiments 

 which man still retains, by the characters which occasionally 

 make their appearance in him through reversion, and by the 

 aid of the principles of morphology and embryology. The 

 various facts to which I shall here allude have been given 

 in the previous chapters. 



The early progenitors of man must have been once cov- 

 ered with hair, both sexes having beards; their ears were 



^^ But I am bound to add that some competent judges dispute this con- 

 clusion; for instance, M. Giard, in a series of papers in the "Archives de . 

 Zoologie Expdrimentale," for 18'J2. Nevertheless, this naturalist remarks, p. 

 281, "L'organisation de la larve ascidienne en dehors de toute hypoth&e et 

 de toute th^orie, nous montre comment la nature peut produire la disposition 

 fondamentale du type vertebr^ (I'existence d'une corde dorsale) chez un in- 

 vert^bre par la seule condition vitale de I'adaptation, et cette simple possibility 

 du passage supprime I'abime- entre les deux sous-r^gnes, encore bien qu'on 

 ignore par oil le passage s'est fait en r^alit^." 



