600 



may be presumed that the changes which take place are somewhat as 

 follows: the blood brought to the limbs by the arteries is collected 

 into a marginal vein which surrounds the free edges of the distal 

 portions of the limb and passes proximally in to stems, one situated 

 on the ulnar (fibular) and the other on the radial (tibial) side. In the 

 anterior extremity the radial vein becomes of less and less importance, 

 and as the digits develop the marginal vein becomes broken up into 

 segments and disappears, while the ulnar vein persists, forming the 

 basilic vein of adult anatomy .... All other veins of the arm are se- 

 condary or tertiary developments, the cephalic and other superficial 

 veins first developing und later the deep veins. At first the cephalic 

 vein, passing over the clavicle, empties into the external jugular, but 

 later it forms a connection with the axillary below, the clavicle, the 

 portion above this connection persisting as the jugulo-cephalic." 



HocHSTETTER (11) has Worked out the development of the veins 

 of the extremities of the Amniotes, and more recently Lewis (12) has 

 done the same for the veins of ths upper extremity of the rabbit. 

 Lewis finds that the primary vein of the Hmb grows distally along its 

 ulnar side, followed later by the secondary or cephalic vein, which 

 Lewis, in opposition to Hochstetter, describes as growing distally 

 from the trunk to the limb, and not vice versa as described by Hoch- 

 stetter. 



Whichever of these embryological views may be correct, it is clear 

 that the chief venous return is along the ulnar side of the limb — em- 

 bryological conclusions, which are fully born out on the adult by the 

 present investigation. 



Conclusions. 



Our conclusions are as follows: 



1. The B.N. A. description of the superficial veins of the superior 

 extremity is more in accordance with the observed facts upon adults, 

 and with the embryological facts, in so far as these are known, than 

 any other descriptive method. It is not, however, in all points of detail 

 absolutely correct, notably as regards its failure to mention the arcus 

 venosus dorsalis, whilst the commencements of the Vv. cephalica et 

 basilica are as stated in this paper, and not as more usually described. 



2. The superficial veins of both upper and lower limbs are homo- 

 logous, and ought to be described as such. 



3. The main venous return in the upper limb is by means of the 

 V. basilica, and all the other veins display a tendency to converge 

 upon this vein. 



