VARIATIONS IN RATE OF DEVELOPMENT 51 



cases, although in most of the embryos injected no indications of 

 these sacs could be observed. 



On the sixteenth day the following observations were made upon 

 sixteen (16} embryos: 



In three embryos the injecta could be forced into the lateral 

 pharyngeal lymphatic from the cardino-Cuvierian communica- 

 tions, as far forward as the caudal end of the otocyst, on both 

 sides of the body; in one embryo the cardino-Cuvierian lymph 

 sac could be injected on one side of the body; in the remaining 

 twelve embryos no definite observations could be made con- 

 cerning the presence of lymphatic anlagen, either at the cardino- 

 Cuvierian or otic points of communication. 



On the seventeenth day the following observations were made upon 

 eleven (11} embryos: 



In four embryos the lymphatics could not be injected even 

 under pressure; in two embryos a small cardino-Cuvierian lymph 

 sac was filled with the injecta on each side of the body; in five 

 embryos the lateral pharyngeal lymphatic could be injected as 

 far forward as the caudal end of the otocyst on both sides of the 

 body and, in three of these embryos, this vessel appeared to 

 communicate with the veins at both the cardino-Cuvierian and 

 otic points of communication. 



On the eighteenth day the following observations were made upon 

 twenty-one (21} embryos: 



In eighteen embryos the lateral pharyngeal lymphatic could be 

 injected on both sides of the body as far forward as the caudal 

 end of the otocyst and, in about half of the embryos, it connected 

 with the veins at the cardino-Cuvierian and otic points of com- 

 munication; in two embryos the lateral pharyngeal lymphatic 

 could be injected on both sides of the body to about the middle 

 of the otocyst, and in one embryo it could be injected only half 

 way to the otocyst on one side of the body and to the caudal end 

 of the otocyst on the other. 



On the nineteenth day the following observations were made upon 

 eighteen (18} embryos: 



In four embryos the subocular lymph sacs could be injected 

 for the first time through the lateral pharyngeal lymphatic, but 



