408 ELEANOR LINTON CLARK 



forced to and fro but they showed no tendency to move ahead 

 in any definite direction. Similarly, in the region just anterior 

 to the leg, such an injection produced no effect. However, 

 when a small number of granules were injected into one of the 

 scattered knobs situated more anteriorly, they soon became 

 dislodged from the point of injection and moved anteriorly, 

 one after the other, always following a definite though some- 

 what tortuous path, previously in\'isible, situated near the 



Fig. 1 Injected chick of 5 days and 12 hours (14.5 nun. before fixation), show- 

 ing character of primary superficial lymphatic plexuses. No circulation. X 5. 



thoraco-epigastric vein. From here the granules moved through 

 the axillary region and disappeared in the depth, beneath the 

 shoulder. This experiment was repeated several times in each 

 embryo of this stage, and in every case the granules behaved 

 in the same manner, moving steadily anteriorly and disappear- 

 ing beneath the shoulder. 



After the circulation had been tested in this way, the same 

 embryo was injected and cleared. In such a specimen it was 

 found that the whole superficial plexus over the pelvis and 

 part of the tail (that part which had contained stagnant blood 



