No. 612] MYXOSPOBIDIAN LIFE CYCLE 



727 



but nothing in his report contradicts the supposition that 

 in Myxidium sp. and in Myxidium hergense there is a 

 close analogy with Davis's and Awerinzew's observa- 

 tions. He also observes the elimination of chromatin and 

 '^eventuell Bildung von Restkernen" (p. 24). These are 

 not incorporated in Fig. 4 for the same reasons I pointed 

 out for Myxidium sp. 



My observations in Chloromyxum leydigi show, further- 

 more, that the cells which form the valves of the spore do 

 not play a part in the development of the final contents of 

 the spore, but are here in this form (comp. Fig. 1) the 

 products of the first division of each gametoc>i;e. In 

 the case of Chloromyxum leydigi two gametocytes form 

 by one di\asion the two spore-membrane-fonning cells; 

 in the three other species, Myxidium sp. (probably Myxid- 

 ium hergense), Ceratomyxa drepanopsettcB and Sphce- 

 rospora dimorpha, one gametocyte forms the one cell, the 

 division products of which are transformed into the valves 

 of the spore. But in all four species these cells have the 

 sole purpose of forming the spore membrane. 



After surveying tlie Figs. 1, 2 and 3, and having com- 

 p.'ii-cd tlioni, I iiave no doubt that the origin of the 

 -pore-mombrane-forming cells is identical in the so-called 

 iiionosporous and disporous forms. Advancing one step 

 fai'ther and taking into consideration tliose forms in 

 whicli two gametocytes form the cells inside each spore 

 (Fig. ly we notice tliat in dealing with the origin and 

 tlie position in tlio developiiient of the s]iore, we have 

 to add nothing. Tlie s])oic-membrano-forming cells are 

 distinguished by their early segregation from tlie game- 

 tocytes and their non-entoring into the series of those 

 cells which are included in tlie s|)ore. The only dilference 

 is that tliese cells do not divide further: if they did, we 

 could en-ily con«^truct tlio di^ix.roiH tyi)0 of .S>//.^ rn.^porn 



