616 W. S. PERRIN. 
further states that, under the highest magnifications the 
spirally wound filament of the polar capsule is often quite 
plainly discernible.! 
Lutz and Splendore (8) describe the presence of the spores 
of a Myxosporidian in the Malpighian tubules and neigh- 
bouring gut of the Brazilian cockroach Periplaneta 
americana, and refer them to the genus Nosema and add 
the species name “periplanetez.” The slight descriptions 
given by Schaudinn and Lutz and Splendore of the spores 
they find in Periplaneta orientalis and Periplaneta 
americana respectively, fit, as far as they go, the spores 
of the Myxosporidian which is the subject of the observations 
recorded in this paper. These observations show, however, 
that the parasite investigated belongs to the genus Pleisto- 
phora,a conclusion impossible to arrive at from a know- 
ledge of the unstained spores alone. 
In spite of the fact that all attempts to infect Periplaneta 
americana with the parasite by feeding them upon the 
infected feces of Periplaneta orientalis have been 
unsuccessful, it is possible that the parasite is identical with 
that described by Lutz and Splendore. I therefore propose 
to retain the specific name periplanete, while referring the 
parasite to its proper genus Pleistophora. The reasons 
for adopting this course will be entered into later, after the 
account of the life-history has been given. 
MATERIAL AND Mernops. 
Pleistophora periplanetz lives in the lumen of the 
Malpighian tubules of Periplaneta orientalis, of which 
it is the sole inhabitant. A few trophozoites are generally to 
be found also in the ileum together with a larger number of 
pansporoblasts containing ripe spores, and the ripe isolated 
1 The polar capsule is a structure occurring in the spores of the Myxo- 
sporidia, containing a filament which is extruded under the stimulus of the 
digestive juices, when the spore reaches the alimentary canal of its host. 
The filament serves to attach the spore to the wall of the alimentary canal. 
