THE DESCENT OF THE PRIMATES 17 



the very early human embryo a peculiar struc- 

 ture which the Germans have called the " Bauch- 

 stiel," or " Haftstiel " of the embryo. Its 

 homologue is found in no other order of Mam- 

 mals. Only lately it has been definitely settled 

 that the monkeys also have it,^ but up to the 

 present time it was a distinguishing feature of 

 which the first origin was as yet quite obscure. 

 This " Haftstiel " or ventral stalk, as it has been 

 called in English, is a string of tissue connecting 

 the very young embryo with its envelope, and 

 differing in many respects from the so-called 

 umbilical cord which at a later period does the 

 same. In those Mammals that have a ventral 

 stalk, the embryo is suspended by it from the 

 very first, whereas in the others this suspension 

 is only secondarily brought about by means of 

 a special outgrowth which travels from the 

 embryo towards the envelope. 



Tarsius throws full light on the obscure origin 

 of the ventral stalk, and at the same time reveals 

 itself to be possessed not only of this very Haft- 

 stiel, which is characteristic of man and 

 monkeys, but also to share with those two 

 another very striking peculiarity by which they 



1 E. Selenka, Studien uber Entwickelungsgeschichte cler 

 Tiere, Heft V , Wiesbaden, 1892. 



9 



