( 378 ) 



by none of the expedients known the polar filament could be indicated 

 in the spores. It is difficult to decide whether the parasite described 

 here is the same as that of Thelohan, but as in neitlier of them a 

 polar capsule is found, and the}" have the same host, in whom, 

 according to Auerbach, (1910) no other niicrosporidiuni lives, it is 

 very likely that these two parasites are identical. The microsporidium that 

 I intend to describe here is however no Glugea, because the trophozoite 

 is directl}' transformed into a pansporoblast, and produces an unequal 

 number of spores, consequently it belongs to the genus Pleistopliora 

 and I propose to call it Flehitophorn tj'ujantea. If P. gigantea is 

 identical Avith Glugea gigantea then the latter name must be dropped, 

 if not, the two names continue to exist beside each other. It will 

 however be hardly possible to decide if this identity exists or not. 

 For this Thelohan's description is too incomplete. 



2. }faterlal and methods. 



The different stages of the development of P. gigantea were found 

 in a big tumour, situated at the ventral side of the head and the 

 thorax of Crenilahrus me/ops. The tumour extended from the ])Osterior 

 margin of the gills along the pectoral tins to the ventral tin. The 

 tumour was caused by hypertrophy of the connective tissue; it did not 

 show any inclination to infiltration, neither the gills and the organs 

 of mouth and thorax, nor the parts of the skeleton were effected by 

 it, it was a pure outgrowth of the skin. The tumour was so iieavy 

 as to deprive the fish of its hydrostatic equilibrium. 



Portions of the periphery and the centre of the tumour were fixed 



Fis;. 1. 



Fig. 2. 



