LYMPH-FLOW AND LYMPHATICS, CHICK EMBEYOS 415 



A few hours later (in embryos measuring 21 mm.) ink granules 

 injected at any point of the superficial lymphatic system move 

 posteriorly into the lymph heart, which beats vigorously. The 

 flow is direct and, compared with earlier stages, rapid. The 



Fig. 5 Chick of 7 days (21 mm.). Stage of rapid posterior circulation into 

 the lymph heart from all of the superficial lymphatics. Injections show large 

 comparatively straight channels over the surface of the body and enlarged chan- 

 nels through the lymph heart, L.H . X 5. 



course of successive granules can be followed readily as they move 

 posteriorly, from a point of injection dorsal to the shoulder, over 

 the side and pelvis into the lymph heart and thence into the 

 coccygeal veins. In the superficial lymphatics of chicks between 



