CERATOMYXA ACADIENSIS. 557 



but the intensity with which the two nuclei are stained is usually, as 

 in the case of Giemsa's stain, markedly different. 



The stage with two nuclei is one of the most, if not the most, fre- 

 quently found of all the stages in the gall bladder. Hence, either this 

 stage must be of long duration or such myxosporidia must be formed 

 in abundance. 



The next stage found is one with three nuclei (PI. I, Fig. 8). Usually 

 two of these are similar in structure and staining reaction to the small 

 dark nucleus of the binucleated stage. On account of the small size 

 of the object and the close proximity of the nuclei to one another, 

 it has not been possible to observe stages in the division of these nuclei. 

 Certain appearances, however, where the two deeply staining nuclei 

 lie close together, lead one to the belief that they have arisen from 

 the division of a single darkly staining nucleus. 



This stage is followed rapidly by a stage with four nuclei (PI. I, 

 Figs. 9, 10), in which two of the nuclei stain very faintly and are 

 usually the larger, while the other two stain very deeply and are 

 usually somewdiat smaller. 



When the stage with fom* nuclei is reached, the protoplasm of the 

 myxosporidium around the two deeply staining nuclei becomes denser 

 and alters its staining reaction (PI. I, Fig. 9), so that corresponding to 

 each of these nuclei a spherical cell containing a single nucleus is 

 formed. These cells may be called " sporoblast-mother-cells " since 

 they later form the sporoblasts. The tW'O faintly staining nuclei 

 remain in the endoplasm of the myxosporidium, and take no part 

 in the formation of the sporoblasts. They may be called "tropho- 

 nuclei." 



During the stage when the myxosporidium contains four nuclei, 

 and possibly in later stages, small chromatin granules are given off 

 from the nuclei of the sporoblast-mother-cells (PI. I, Fig. 10), first 

 into the protoplasm of these cells and later into the surrounding endo- 

 plasm of the myxosporidium. Here, apparently, they are absorbed, 

 since they are not usually found during the later stages of spore 

 formation. 



The sporoblast-mother-cells continue to divide until twelve are 

 formed (PI. I, Figs. 13-17). These twelve cells then come together 

 and form the sporoblasts. 



If this account be compared wdth that of Awerinzew (:09) for C. 

 drepanopsettae, a number of differences in the two species will be 

 seen. In the binucleated stage described, but not figured, by Awerin- 

 zew the two nuclei are similar in all respects. He says (:09, p. 78): 



"Das Amoboid mit zwei Kernen bildet sich ohne alien Zweifel aus 



