PHENOMENA ACCOMPANYING FERTILIZATION 



549 



germinal giving rise by division to "microgametes" and macro- 

 gametes which fuse after "reduction." Mavor (191(i) working with 

 an alHed species (Ceratomyxa acadiensis) found uninucleate \oung 

 forms which, upon the first division of the nucleus, give rise to 

 dimorphic nuclei as described by Awerinzew. The fusion of "gam- 

 etes" which Awerinzew described was confirmed in part by Keys- 

 selitz (1908) in connection with Myxohohis jjfeifferi. Here the 

 pansporoblasts which Keysselitz names the "propagation" cells, 



Fig. 2.30. — Amaha dipJoidea. The ordinary vegetative individual has two nuclei 

 which divide independently at cell di\'ision. With encystment these nuclei form 

 spindles (B) and the cells divide (C, D); the two pairs of nuclei then unite, forming 

 two fusion nuclei after which the cell bodies reunite, thus forming the vegetative 

 binucleated cell. (After Hartmann and Niigler.) 



arise in the protoplasm of the adult organisms in the same manner 

 as in other Myxosporidia, but the nuclei, and with them the cell 

 body of the germinal area, divide (Fig. 229, A. B, C). The pro- 

 pagative cells later unite 2 by 2 and are at first separated by a thin 

 cell wall, which later disappears. Within this united mass the 

 nuclei divide until there are 14 as in Sphceronu/.va. Such cases of 

 fusion are interpreted by Erdmann (1917) as plastogamous in 

 character. 



