DEVELOPMENT OF EGG FRAGMENTS IN CEREBRATULUS. I 27 



mitotic figure. Consequently in some cases the fragments were 

 quite small. In this series all the defective larvae were more 

 abnormal than in the preceding. The abnormalities may be 

 classified as follows : 



Defect in apical JLarvee with supernumerary apical organ 4 



' ' no apical organ I o 



" ciliated lobes indented or not well developed 16 



organ. ( 



Defect in ciliated J 



lobes. 



Defect in gut. 



I 



only one ciliated lobe II 



no gut 6 



no oesophagus 5 



no stomach I 



stomach cutoff from oesophagus 2 



gut not well developed 7 



14 



27 



r 21 



FlG. 2. 



The disturbance of the apical organ (2,B and 26") is of special 

 interest, indicating that its basis covers quite a large area over the 

 animal pole, since in this series it was impossible to cut off cyto- 

 plasm from the top of the egg. While in Series A the defective 

 part was chiefly restricted to the apical organ, we find that in the 

 stage under consideration the abnormalities extend to the ciliated 

 lobes and gut also. As will be seen from the above table, a 

 large number of the defective pilidia have abnormal ciliated 

 lobes ; in some, one of the lobes is very short (2^?), while in oth- 

 ers the lobes are indented (2/T), reminding us of Pilidiinn braii- 

 chiatinn. Quite commonly one lobe is entirely wanting (2 A, 2C 

 and 2/7). The defect in the gut is remarkable. In a few larvae 



