THE HUMAN PLACENTA. 169 



ton's jelly "), in which are contained the remnants of the 

 yelk- vessels and of the great navel vessels ; the two navel 

 arteries which convey the blood of the embryo to the pla- 

 centa, and the great navel vein which brings back the blood 

 from the latter to the heart. The numerous fine branches 

 of these embryonic navel vessels pass into the branched 

 chorion-tufts of the foetal placenta, and with these, finally, 

 grow, in a very peculiar way, into large blood-filled cavities, 

 which spread themselves in the uterine placenta and con- 

 tain blood from the mother. The anatomical relations, very 

 complex and difficult to comprehend, which are developed 

 between the embryonic and the maternal placenta, exist in 

 this form only in Man and in the higher Apes, while in all 

 other Deciduous Animals their form is more or less different. 

 The navel cord, also, is proportionately longer in Man and 

 in Apes than in other Mammals. 



As in these important characters, so also in every other 

 morphological respect, Man appears as a member of the 

 order of Apes, and cannot be separated from the latter. The 

 great originator of systematic description of nature, Karl 

 Linnaeus, with prophetic penetration, united Men, Apes, 

 Semi-apes, and Bats in a single natural division, under the 

 name of Primates, that is, the first, the lords of the animal 

 kingdom. Later naturalists dissolved this order of Primates. 

 The Gottingen anatomist, Blumenbach, first placed Man in 

 a special order, which he called that of Two-handed Animals 

 (Birtiana) ; in a second order, he united Apes and Semi- 

 apes under the name of Four-handed Animals (Quad- 

 rumana), while a third order included the distantly related 

 Bats (Chiroptera). The separation of the Bimana and 

 Quadrumana was retained by Cuvier and most succeeding 



