Chap. VI.] AFFINITIES AND GENEALOGY. 199 



once served as a float. The clefts on the neck in the embryo 

 of man show where the branchiae once existed. At about 

 this period the true kidneys were replaced by the corpora 

 wolffiana. The heart existed as a simple pulsating vessel ; 

 and the chorda dorsalis took the place of a vertebral col- 

 umn. These early predecessors of man, thus seen in the 

 dim recesses of time, must have been as lowly organized 

 as the lancelet or amphioxus, or even still more lowly or- 

 ganized. 



There is one other point deserving a fuller notice. It 

 has long been known that in the vertebrate kingdom one 

 sex bears rudiments of various accessory parts, appertain- 

 ing to the reproductive system, which properly belong to 

 the opposite sex ; and it has now been ascertained that at 

 a very early embryonic period both sexes possess true 

 male and female glands. Hence some extremely remote 

 progenitor of the whole vertebrate kingdom appears to 

 have been hermaphrodite or androgynous. 23 But here we 

 encounter a singular difficulty. In the mammalian class 

 the males possess in their vesiculre prostatica rudiments 

 of a uterus with the adjacent passage ; they bear also 

 rudiments of mamma?, and some male marsupials have 

 rudiments of a marsupial sack. 24 Other analogous facts 

 could be added. Are we, then, to suppose that some ex- 

 tremely ancient mammal possessed organs proper to both 

 sexes, that is, continued androgynous after it had acquired 



23 This is the conclusion of one of the highest authorities in com- 

 parative anatomy, namely, Prof. Gegenbaur : ' Grundziige der vergleich. 

 Anat.' 1870, s. 876. The result has been arrived at chiefly from the 

 study of the Amphibia ; but it appears from the researches of YValdcyer 

 (as quoted in Humphry's c Journal of Anat. and Phys.' 1869, p. 161), 

 that the sexual organs of even " the higher vertebrata are, in their early 

 condition, hermaphrodite." Similar views have long been held by some 

 authors, though until recently not well based. 



24 The male Thylacinus offers the best instance. Owen, ' Anatomy 

 of Vertebrates,' vol. hi. p. '111. 



