86 H. D. SENIOR 
III. BRIEF DEVELOPMENTAL HISTORY OF THE INDIVIDUAL 
ARTERIES 
A. Axis. This artery is a branch of the dorsal root of the a. 
umbilicalis, its presence has been noted by Tandler as early as 
the stage of 5mm. ’03). At the stage of 6 mm. it terminates by 
giving origin to the r. perforans tarsi and to the rete plantare. 
The axial artery has three rami communicantes, and gives 
origin to three rami perforantes as follows: 
The r. communicans superius, from the a. femoralis, joins it 
near the hiatus tendineus shortly before the stage of 14 mm. 
The r. communicans medius, from its own branch the a. 
peronaea posterior superficialis, has joined it near the distal 
border of the m. popliteus at the stage of 22 mm. 
The r. communicans inferius, from the a. peronaea posterior 
superficialis, joins it, near the distal border of the m. tibialis 
posterior, between the stages of 17 and 18 mm. 
The r. perforans cruris arises between the stages of 13 and 
14 mm. 
The r. perforans artertae peronaea arises between the stages 
of 18 and 22 mm. 
The r. perforans tarsio is present at the earliest stages of de- 
velopment at which the axial artery has been observed. 
Two points have been marked upon the axial artery at the 
stage of 14 mm. which may be used for the convenient sub- 
division of the axial artery into three parts. These points 
correspond to the termination of the r. communicans superius 
and to the origin of the r. perforans cruris, respectively. 
The respective parts of the artery are defined and named as 
follows: The part upon the proximal side of the termination of 
the r. communicans superius is the a. ischiadica, while that 
upon the distal side, of the origin of the r. perforans cruris is 
the a. interossea. That part intervening between the other two 
is the a. poplitea profunda. Further information regarding the 
axial artery may be found under the headings devoted to the 
description of its respective parts. 
A. dorsalis pedis. ‘This artery is a channel through the em- 
bryonic rete dorsale. Its importance dates from the appearance 
