1916.] NATURAL SCIENCES OF PHILADELPHIA. 33 



artifact, it indicates that they arc in no sense encysted, but are 

 rather naked masses of cytoplasm. This irregularity of outline, 

 however, is not necessarily associated with the supposed fertilization, 

 since many of the macrogametes which showed the conspicuous 

 chromatin body had maintained their smooth and regularly curved 

 contours. 



Discussion. 



If the evolution of the macro- and microgametocytes of S. muris, 

 as outlined above, be compared with that of Coccidium schubergi, as 

 worked out by Schaudinn (1900) it will be seen that there is a very 

 close resemblance. Thus, in both, the chromatin of the micro- 

 gametocyte becomes divided into very small particles which collect 

 in masses at the periphery and there condense to form the micro- 

 gametes. This mode of division is designated by Minchin (1912) 

 as chromidial fragmentation, the minute granules themselves being 

 the familiar chromidia. Similarly, in both the sarcosporidian and 

 the coccidian, the nucleus of the macrogametocyte discharges chro- 

 matic granules into the cytoplasm where they are apparently 

 absorbed. 



On the other hand, there are many marked differences. In the 

 first place, in S. muris the male cell loses most if not all of its cyto- 

 plasm, the formation of the microgametes taking place in what is 

 morphologically the nucleus. Hence, there is not only no increase 

 in size of the parasite after it gains an entrance into a host cell, but 

 actually a loss of substance. It is somewhat the same with the 

 female cell which, while it gains in bulk, does so to a rather limited 

 extent. This is in marked contrast to the phenomena displayed by 

 Coccidium schubergi, in which the macro- and microgametocytes are 

 many times bulkier than the -merozoites from which they took origin. 



The sarcosporidian runs through its sexual development within 

 from 9 to 18 hours, while judging from the data given by Schaudinn 

 (p. 217), the coccidian requires about two days. 



The resemblances and differences between these two parasitic 

 Protozoa are here merely pointed out. The resemblances are 

 certainly very striking, but it seems premature to assign any signifi- 

 cance to them. It is conceivable that they indicate a genetic rela- 

 tionship between the Sarcosporidia and Coccidia, but it is just as 

 likely that we are dealing with phenomena broader than those 

 suitable for connecting groups of the value of the Coccidia and 

 Sarcosporidia. The problem is one that requires more evidence 

 before any far-reaching conclusions are warranted. 

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