MICROSYMBIOSIS 79 



More recently, Meyer ('25) has investigated Cyclostoma 

 elegans and a number of related species. He was able to 

 cultivate bacteria from the animals, but was not convinced 

 of their relationship to the bacteria in the "purinocytes." 



In the small group of the Ascidia {Molgulidii) urate- 

 storage kidneys are also found. These storage cells con- 

 tain a fungus in place of the bacteria, according to Buchner. 

 They produce both myceUa and spores. 



]\Iicrosymbiosis is very widely distributed in the insects, 

 being found in all the orders of this group. The definitive 

 symbionts are bacteria in a large number of cases. We 

 shall discuss here only a few of the more representative 

 cases, and such relationships as have a more intimate 

 bearing on Symbionticism. 



All of the species in the family Blattidii harbor symbion- 

 tic bacteria. Blochmann in 1887 was the first to describe 

 bacterial symbionts in these insects. In Blatta germanica 

 and Periplaneta orientalis he found that the central part 

 of the fat bodies was composed of cells devoid of fat. These 

 cells contain small rod-shaped bodies which were of un- 

 doubted bacterial nature. When he failed in his attempt 

 to cultivate them, he concluded that this was evidence of 

 their intimate dependence upon the insect organization. 

 Cuenot ('92), Prenant and Henneguy ('04) investigated 

 these cells in the fat bodies, and beheved that the rod- 

 shaped structures represent metaboHc products. Mercier 

 ('06) was able to cultivate them outside of the body and 

 definitely estabhshed their bacterial nature. Frankel, a 

 pupil of Buchner, investigated a large number of species, 

 and demonstrated the presence of symbiotic bacteria in 

 all. Buchner proposed the name ''Bacteriocytes" for all 

 cells containing bacteria. The bacteriocytes vary in 

 shape and arrangement in different species. The bacteria 

 also vary in size in the bacteriocytes of different species. 

 Philiptschenko ('07) studied these insects, and showed that 



