DISTRIBUTION OF SUBCUTANEOUS VESSELS IN GANOIDS IO5 



ing the cephalic trunk with the yellow mass, it simply pushed 

 back the blue, forming the conditions described above, viz., of 

 certain areas of one color and other regions of a mixture. 



Whether these conditions were obtained after this manner or 

 were brought about through the media of peripheral communi- 

 cations with the nutrient arteries, might possibly be settled by 

 removing a branchial arch from a large Polyodon, and after 

 securely ligaturing both ends of the arch proper, plug up one 

 end of the so-called branchial lymphatic trunk and inject from 

 the other, but most unfortunately, however, these subcutaneous 

 branchial vessels were not studied with any detail, until after I 

 was removed some 2,000 miles from the source of material. 

 Except for the fact that nutrient arteries were found on the 

 arch, and no nutrient veins were observed, unless the so-called 

 lymphatics function for both veins and lymphatics, I can see 

 no reason for maintaintng that hypothetical peripheral connec- 

 tions exist between the nutrient arteries and the so-called bran- 

 chial lymphatics. Certainly the methods resorted to in this study 

 do not justify it ; in fact, the numerous connections with the 

 inferior jugular and the two with the jugulars rather forbid such 

 a view. 



A point slightly favoring the hypothesis that the branchial 

 subcutaneous vessels function as veins, is the fact, that a sec- 

 tion through a main branchial lymphatic trunk (Fig. 28) always 

 shows a predominance of red corpuscles. The ratio of red to 

 white is 37 to 22, which, however, lacks considerable of being 

 so overwhelming as one would expect to find in a vein. For 

 example in the inferior jugular, into which these vessels ter- 

 minate ventrad, the ratio of red to white is about 12 to i and in 

 the mesenteric vein one has to look some time to find a leuco- 

 cyte ; while in the cephalic trunk, into which these vessels 

 culminate dorsad, the red corpuscles are very scarce, the ratio 

 of white to red being 153 to 8. Hence from purely histological 

 grounds one might infer that the branchial lymphatic trunks 

 discharged themselves mainly into the inferior jugular, but the 

 fact that none of the branchial arch trunks terminates in the in- 

 ferior jugular, while some of them do empty directly into the 

 cephalic trunk ; and the additional observation that the branchial 



