146 PATTEN. 
going on rapidly and extensively in this embryo, there are numerous karyokinetic 
figures in both the ectoderm and mesoderm at the posterior end of the body. 
Fic. 107, X 60. A very small, circular embryo, with a bare trace of cephalic 
lobes and oesophagus, the latter appearing as a white spot with faint bands on 
either side, which probably represent the anterior extensions of the nerve-cords. 
Two pairs of appendages are present (second and third thoracic ?) and back of 
them are traces of other appendages. The abdominal invagination is small, but 
quite deep. 

