AFFINITIES AND GENEALOGY. 183 



them as formidable weapons. At a much earlier period the 

 uterus was double ; the excreta were voided through a 

 cloaca; and the eye was protected by a third eye-lid or nic- 

 titating membrane. At a still earlier period the progenitors 

 of man must have been aquatic in their habits; for morphology 

 plainly tells us that our lungs consist of a modified swim- 

 bladder, which once served as a float. The clefts on the 

 neck in the embryo of man show where the branchiae once 

 existed. In the lunar or weekly recurrent periods of some 

 of our functions we apparently still retain traces of our 

 primordial birth-place, a shore washed by the tides. At 

 about this same early period the true kidneys were replaced 

 by the coi-pora wolffiana. The heart existed as a simple 

 pulsating vessel; and the chorda dorsalis took the place of 

 a vertebral column. These early ancestors of man, thus 

 seen in the dim recesses of time, must have been as simply, 

 or even still more simply, organized than the lancelet or 

 amphioxus. 



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 possessed true male 

 and female glands. Hence some remote progenitor of the 

 whole vertebrate kingdom appears to have been hermaph- 

 rodite or androgynous.* But here we encounter a singu- 

 lar difficulty. In the mammalian class the males possess 

 rudiments of a uterus with the adjacent passage, in their 

 vesiculae prostaticae; they bear also rudiments of mammae, 

 and some male Marsupials have traces of a marsupial sack. \ 

 Other analogous facts could be added. Are we, then, to 

 suppose that some extremely ancient mammal continued 



This is the conclusion of Prof. Gegenbaur, one of the highest 

 authorities in comparative anatomy; see " 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 Wald- 

 eyer (as quoted in " 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 

 sf)me authors, though until recently without a firm basis. 



f The male Thylacinus offers the best instance. Owen, " Anatomy 

 of Vertebrates," vol. iii, p. 771. 



