Frederic T. Lewis 115 
vein, Fig. 7, p. 107. At 20 days, Fig. 8, p. 108, the cephalic vein has 
acquired its new and permanent orifice near the axillary vein. The 
jugulo-cephalic vein marks its former outlet. 
With the differentiation of the digits, the primitive ulnar vein becomes 
greatly reduced by the loss of its distal portion. This is shown in Fig. 
4, At 17 days, Fig. 7, p. 107, the continuity of the primitive ulnar vein 
has been interrupted at the elbow, resulting in further reduction. The 
vein then extends from the elbow to the superior vena cava, following the 
brachial artery, from around which it receives small branches. In the 
20-day embryo, Fig. 8, p. 108, the brachial vein (proximal part of the 
primitive ulnar) is continued down the forearm following the ulnar 
artery. If we may judge from the position of this vessel, there has been 
a re-establishment of the course which was interrupted in the younger 
embryo. Hochstetter, however, states (p. 28) that in rabbits the fore- 
arm section of the primitive ulnar vein seems to disappear, although in 
man (p. 35) the corresponding vessel is preserved throughout, and forms 
the basilic vein of the forearm and arm, the axillary and subclavian veins. 
The question arises whether the primitive ulnar vein should be de- 
scribed as producing the deep ulnar, brachial, and axillary veins, naming 
it for the adjacent arteries, or as forming the basilic and axillary veins, 
considering the cutaneous vein of the corresponding region as its more 
direct derivative. This uncertainty calls attention to the fact that both 
the superficial and deep sets of veins have a common origin, and that be- 
fore their separation the embryonic vein may properly be called either 
brachial or basilic. The rabbit of 20 days is characterized by the estab- 
lishment of this brachial (or basilic) vein. 
In the development of the veins of the arm three stages have been dis- 
tinguished : 
Ist. The stage of the primitive ulnar vein. 
Ba EE SS cephalic vein. 
3d. “~ “ “ “ brachial vein, the cephalic vein persisting. 
VEINS OF THE POSTERIOR EXTREMITY. 
A rabbit of 1014 days (Harvard Collection, No. 199) has a very large 
umbilical vein which sends branches into both limbs. Those in the leg 
form a net which connects with the posterior cardinal vein, still a minute 
vessel in the caudal end of the body. From the network a vein is devel- 
oped, which after following the periphery of the limb and passing along 
its posterior or fibular border, empties into the cardinal vein. This vessel 
may be called the primitive fibular vein. The original connections of the 
