No. 3.] NERVOUS SYSTEM OF CYNTHIA PARTITA. 109 



It would be difficult to give the proportion of cells found 

 which contained centrosomes, as in many specimens after stain- 

 ing no such structure can be proved. The nucleus, although 

 excentric, appears ovoid or circular, and no concentric arrange- 

 ment of the cytoplasm can be observed. In such cells, how- 

 ever, the centrosome may exist as a granule, although no such 

 state has been proved. 



Several very young animals from two to three mm. long 

 were killed shortly after metamorphosis. In such specimens 

 the ganglion cells, although nearly as large as in the adult, 

 contained nuclei much larger in proportion than those contained 

 in the adult cells. The nuclei were much richer in chromatic 

 material than in the adult. The most striking feature noticed 



Fig. 6. — Cross-section of brain {Cynthia) shortly after metamorphosis, showing centrosomes 

 in ganglion cells, p.c, large peripheral cells ; c.t., connective-tissue cells. Von Rath. 

 Iron-haematoxylin. Camera drawing. 1^5 x oc. 6 (Zeiss). 



was the fact that a very large proportion of the cells was found 

 to contain centrosomes, although in most cases the sphere and 

 radiations were lacking. It cannot be positively stated that all 

 ganglion cells at this stage contain centrosomes, but certainly 

 a very large proportion do, as can be seen by a glance at Fig. 6. 

 The centrosome in these cells is usually double, i.e., two cen- 

 tral bodies are found. There seems to be no common axial 

 relation between the direction of the two bodies and the long 



