56 H. D. SENIOR 
all mammalian forms is a question to which direct observation 
of the vessel has not yet furnished an answer. Much indirect 
evidence bearing upon this subject is furnished by Zuckerkandl’s 
comparative study of the arteries of the leg which appeared in 
1895. 
The study in question, although it is mainly concerned with 
the relations of the adult arteries, is influenced throughout b4 
embryological considerations. It includes, in fact, a study of 
the arteries in a series of vertebrate embryos in which the 
mammalia are represented by the rabbit and cat. Zucker- 
kandl’s work is obviously based upon the conception of the 
identity of the course of the axial artery throughout the mamma- 
lian series. It may be said that the general results of the 
investigation are greatly in favor of the correctness of the author’s 
conception. 
The principal relations of the axial artery of the human 
embryo have been established by the present study. An ade- 
quate account of the relations of this and other arteries of the 
developing limb of one of the quadruped mammals would be of 
great value for purposes of comparison. 
The only consecutive account which has been given of the 
development of the arteries of the pelvic hmb in any mamma- 
lian form is that of DeVriese, which appeared in 1902. It deals 
with the human embryo. The other papers contained in the 
literature of the subject are concerned with isolated stages in the 
development of one or more forms rather than with a complete 
history of the arteries of any particular mammal. 
Hochstetter showed for the first time, in 1890, that the primi- 
tive artery of the mammalian thigh, which he termed the a. 
ischiadica, follows the course of the n. ischiadicus in the embryos 
of both the cat and the rabbit. He also described the develop- 
ment of the a. femoralis, which, appearing at a later stage, 
supersedes the proximal part of the a. ischiadica as the chief 
artery of the thigh. The secondary assumption of the original 
function of the a. ischiadica by the a. femoralis was shown to 
oecur in man by DeVriese in 1902. 
