274 



that amitotic division is an important factor in regulatory development 

 in Tubularia. 



Miss Stevens ('01) has noted the occurrence of mitosis during 

 regulation in this form but apparently it is found chiefly during the 

 earlier stages. 



Corymorpha palm a. My results on this species are very 

 similar to those on Tubularia. Sections of developing hydrauths in 

 pieces undergoing regulation show frequent amitoses and thus far only 

 one mitosis has been seen but the earliest stages have not yet been 

 examined. The amitoses appear to be especially abundant ia the 

 regions of the developing tentacles. Figure 2 shows a number of 



VII 



cases, all occurring in a single section. Nos. I — V are from the 

 ectoderm, VI— VIII from the entoderm. No. IX, in which the two 

 halves show a marked ditference in structure and tingibility although 

 no visible boundary between them exists, is given as perhaps re- 

 presenting an early stage in the process of division. Here, as in 

 Tubularia it seems impossible to account for the large number of 

 nuclei in the new hydranth by migration, and mitosis is certainly rare. 



