﻿180 Proceedings of the Royal Physical Society. 



metliod of spore development in Haplosporidium scolopli} 

 A similar development seems to be implied in the description 

 of the sporozoites of Coelosjooriclium chydoricola^ and suggested 

 in the case of Icthyosporidium gasterojphilum. There is no 

 inherent impossibility in this method of development, and 

 the case of Saplosporidium scolopli seems to be well founded. 

 Nevertheless I do not see any evidence in the parasite at 

 present in question to indicate that it occurs here; the 

 mere increase in size is by itself not a point of any weight 

 in this direction. Evidence against it is, I think, afforded 

 in this particular instance in the persistence of the fine rays 

 between the karyosome and the membrane. 



Division of the nuclei may occasionally be seen, and it 

 may be noted that it occurs simultaneously throughout the 

 whole animal. It is difficult to obtain very precise informa- 

 tion as to the finer details of the nuclear division, partly 

 owing to the extreme smallness of the nucleus and partly 

 to the fact that although an immense number of parasites 

 have been reviewed, stages with dividing nuclei have only 

 occasionally been met with in the material at my disposal. 

 In the case of the Protozoa, where a happy diversity of 

 method is found in the process of nuclear division, it is 

 unwise to form conclusions without a large number of 

 observations to draw from. It may therefore suffice to 

 state here that the nucleus appears to divide by a modified 

 form of mitosis, without, as far as I can see, the formation 

 of an equatorial plate. Figs. 4 and 5 illustrate the process. 



The smallest forms hitherto met with show two nuclei. 

 They are spherical or subspherical bodies — with the 

 appearance of being composed of soft protoplasm. They 

 have no well-marked envelope, and seem only to be bounded 

 by a thin membrane. The nuclei are identical with those 

 described above. These small parasites are usually found 

 lying together in groups. They sometimes give the appear- 

 ance of being inside a tissue cell, but certainly lie between 

 the cells when they are a little larger (Fig. 6). 



The development of such a small creature into the larger 



1 Arch. Zool. Exp., T. iv., No. 3, p. 113. 



2 lUd., T. iv., No. 3, p. 142. 



