A GREGARINE, DIPLOCYSTIS, IN THE 
HAEMOCOELE OF THE ROACH, 
BLABERUS CRANllFER BURM. 
By W. L. Nutting 
Biological Laboratories, Harvard University 
Until such time as the genus of giant cockroaches, Blaher- 
us, is better known, both taxonomically and biologically, it 
would be useless as well as impossible to present even a 
reliable list of their internal parasites. Furthermore, con- 
sidering our meager knowledge of the protozoan faunas of 
some of our commonest roaches, the mere identification of 
forms in exotic roaches such as these, must often involve 
a certain amount of original research. However, since B. 
cramifer has gained considerable standing as a general 
laboratory animal in many institutions, attention should be 
called to a rather unusual acephaline gregarine, probably a 
Diplocijstis, which has been noted in some cultures of this 
insect. Gregarines seem not to have caught and held the 
attentions of many protozoologists, but the encountering of 
such large, immobile bodies as Diplocijstis during dissection 
of a cockroach, seldom fails to arouse the curiosity of the 
entomology student. 
The stages of this gregarine most commonly seen are 
the paired trophozoites, and the cysts following the com- 
plete fusion of these pairs (fig. 1). Both stages are opaque 
white and smooth, and frequently attain a length or maxi- 
mum diameter approaching 2 mm. Staining with haema- 
toxylin reveals the nuclei and a coarsely granular cytoplasm 
in these otherwise almost characterless organisms. From 
one to 12 or more paired trophozoites or cysts may be found 
in the haemocoele among lobes of the fat body, generally 
near coils of the hind gut, but occasionally in the thorax. 
The early stages of Diplocystis schneideri Kunstler are 
found in the mid gut epithelium of Periplaneta amencana 
until sufficiently developed to enter the host’s body cavity. 
The cannibalistic tendencies of roaches insure the parasite’vS 
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