1953 I 
Nutting — Gregay'ine in Blaberm 
127 
perpetuation through the ingestion of mature spore-con- 
taining cysts along with the tissues of weakened or dead 
infected individuals. This mode of infection probably ex- 
plains why heavy infections in this gregarine are rare, even 
in crowded cultures of roaches, for crowding favors the 
growth of enormous infections of many gregarines whose 
cysts are passed with the feces. 
I. Paired 1 rophozoitos (loft) ami early cyst of Diplncy-hs sj). 
fro(!i till haomocoeie of Blnberns cmniijcr, X 13 . 
Since the mid gut and bind gut of B. craniifei' harbor at 
least two cephaline gregarines, along with a number of 
other protozoans and nematodes, it is impossible at present 
to assess the effect of any one of them on the health of the 
roach. The presence of D. schneideri in Periplaneta raises 
doubts as to the specific identity of the Diplocystis in labor- 
atory cultures of Blaberus. Large numbers of Periplaneta, 
raised adjacent to Blaberus cages, have been examined for 
the parasite with negative results. However, the identifi- 
cation of the Diplocystis in Blaberus, either as schneideri 
or as some other species, might involve carefully controlled 
and lengthy infection experiments. Although the life cycle 
of many gregarines is known, detailed information on their 
biology and host specificity is extremely limited. 
It might be added that the gregarines most often observed 
by entomologists belong to the tribe Cephalina. These are 
commonly found in the alimentary canal of arthropods and 
other invertebrates. Some may accidentally reach the haem- 
ocoele, but only a few are regularly found there. On 
the other hand, members of the Acephalina are confined 
chiefly to the haemocoele and associated organs. Most of 
the known acephalines are found in annelids, but a few are 
known from echinoderms and insects. I wish to thank Dr. 
Victor Sprague of Black Mountain College, Black Moun- 
tain, N. C., for examining the gregarine fauna of Blaberus, 
