No. 612] MYXOSPORIDIAN LIFE CYCLE 



735 



with pansporoblast (exception, Mercier, Myxoholus pfeif- 

 feri), the first division products of the gametocyte or 

 gametocytes form the pansporoblastic membrane or, if 

 degenerated, its nuclei. This division is a heteropole di- 

 vision and forms highly chromatic small cells or nuclei 

 which never intermingle with the cells inside the pan- 

 sporoblastic membrane (exception, Schroeder). 



On the basis of these facts, we need only state that the 

 heteropole division has no connection whatsoever with a 

 reduction division, as Keysselitz tentatively suggested. 

 This conspicuous division produces the Hiillzellen or 

 Hiillzellenkerne, and it may not be impossible that in the 

 case of 8ph(Eromyxa sahrazesi these small chromatin cells 

 do not intermingle with the others and divide up, though 

 the author mentions it on page 366. They originate, ac- 

 cording to Schroeder 's second interpretation, in the same 

 manner as most authors describe, but divide together with 

 the big cells until twelve cells are present in the pansporo- 

 blast; they then take their accustomed place inside the 

 sporoblast membrane and are easily recognizable. This 

 apparent exception merits further investigation. 



We maintain our conclusion that the Hiillzellenkerne 

 or the Hiillzellen are identical with the spore membrane 

 forming cells of the non-disporoblastic polysporous forms. 

 They have the following features in common : they are the 

 first division products of the gametocytes; they do not 

 intermingle with the other cells inside the spore; they 

 form the envelope, in one case of the spore, in the other 

 of the pansporoblast. They are neither somatic residual 

 nuclei nor Restkerne nor reduction nuclei. They are 

 cells which have a tendency to degenerate in some disporo- 

 blastic forms when their functions are taken up at an 

 early period by the valve cells or spore-membrane-form- 

 ing cells. 



Tt remains, as the last part of our discussion, to deal 

 fully with the significance of those darkly stalniiiu' masses 

 which have been described as ''Rodnotioiiskoriu"" or 

 ''Restkerne" ''imide the sporoblast." Tn the following 

 table we give a short survey of the known facts. 



