100 OTTO F. KAMPMEIER 
The further development and thickening of the muscle coat 
is not consummated until some time after metamorphosis, for 
even in the young toad it is not conspicuous and is composed of 
only three or four cell layers. 
; <j Se aa we EE eee 
lym. com. jug: ef lat. 
_ \ym, lat. Bee 
Fig. 20 Same, in a 9-mm. embryo of Bufo vulgaris (K. E. C., series B 13, 
slide 3, section 14). 340. *, the common segment of the jugular and lateral 
lymphatics by expansion have again come in contact with the lymph heart; 
lym. lat., a ventral branch of the lateral lymphatic (lymphatica lateralis) and con- 
tinuous with the dorsal one at a further level. Other references as before. 
The intima, too, of the lymph heart is slow in acquiring its 
definitive character, which is not attained until approximately in 
15- or 16-mm. stages. Even in 10- or 11l-mm. embryos the 
endothelial cells show little advance over those present in the 
heart of somewhat younger individuals. Some do have the finished 
