of Pleistophora periplanetae, Lutz and Splendore. 205 



The protoplasm of the trophozoite is frequently differentiated 

 into a denser, more deeply staining outer layer or ectosarc, and an 

 internal non-fluid layer or endosarc. Pseudopodia occur frequently 

 and are generally lobose, though elongated and pointed pseudo- 

 podia are also found. The endosarc may be hyaline or reticular 

 in structure. Vacuoles of varying sizes are of frequent occurrence. 

 Granules appear to be absent, but large mucoid looking inclusions 

 are occasionally to be seen within the trophozoite. In tropho- 

 zoites stained with Giemsa's eosin-azur mixture two kinds of nuclei 

 are to be distinguished, one kind which stains bright red and 

 another which stains a deep violet. The nuclei staining deep 

 violet are very compact and frequently contiguous to a small area 

 of protoplasm staining bright blue. The nuclei which stain bright 

 red are generally reticular in structure although occasionally com- 

 pact. With Delafield's haematoxylin the violet nuclei stain very 

 intensely. 



Two methods of reproduction can be distinguished in Pleisto- 

 phora periplanetae, one subserving auto-infection, and one resulting 

 in the production of coated spores, which gain the exterior per anum 

 and presumably infect fresh hosts. 



Auto-infective methods of Reproduction : Multiplication of the 

 parasite within the host may be effected apparently in four ways : 

 (1) the young uninucleated trophozoite may divide amitotically 

 into two. (2) The nuclei of a young trophozoite may multiply ami- 

 totically and proceed to the periphery of the cell, where the proto- 

 plasm rounds itself off about each nucleus, the trophozoite finally 

 breaking up into a number of uninucleated spores. This method 

 of reproduction recalls the schizogony of the Telosporidia. (3) A 

 multinucleated trophozoite may divide into two by a process of 

 simple fission. (4) Portions of a large multinucleated trophozoite 

 may separate themselves from the parent cell and begin an inde- 

 pendent existence. The fragments budded off may have one or 

 several nuclei, but a trophozoite does not appear to produce buds 

 with one and many nuclei at the same time. Doflein describes 

 a similar process of fragmentation in Olugea lophii, and terms it 

 plasmotomy. Division of a trophozoite into two pieces, i.e. ordi- 

 nary binary fission he terms simple, division into more than two 

 fragments, multiple plasmotomy. The production of uninucleated 

 spores from a trophozoite by budding does not appear to have 

 been hitherto recorded among the Myxosporidia. 



Spore formation: All the above methods of reproduction sub- 

 serve auto-infection, but resting spores are also produced, which 

 presumably bring about the infection of fresh hosts. Among the 

 Myxosporidia it is usual, as a preliminary to sporulation, for the 

 trophozoite to produce a number of internal buds, which give rise 

 to a varying number of spores, the production of spores continuing 



