514 ROBERT W. HEGNER 
were only from 4 to 5u long and were not so regularly arranged 
in bundles as in the former species He at first supposed these 
bacteria-like bodies to be cytoplasmic structures, but, aiter 
observing them in various stages of division, expressed the 
opinion that they are symbiotic bacteria. f 
Bodies of a similar kind have been observed in many other 
insects. Those that occur in the cockroaches most closely re- 
semble the bacteria-like rods in the ovarioles of ants. These 
likewise were first discovered by Blochmanh (’87, ’92) in Peri- 
planeta orientalis. They occurred not only in the eggs but also 
among the blastoderm cells and in the spaces formed by the lique- 
faction of the yolk in the embyros. Later they were observed 
in the anlage of the fat body where they persist in the adult 
stage. Wheeler (’89) described them in the ‘Keimhautblastem’ 
of Blatta germanica as ‘“‘minute rod-shaped bodies so numerous 
in the surface protoplasm as to make it appear reticulate. They 
look like bacillar micro-organisms and stain deeply.”’ 
Mercier (07) has subjected these bacteria-lke rods in Peri- 
planeta orientalis to careful study. He agrees with Blochmann 
regarding their distribution and confirms Blochmann’s statement 
that they multiply by division. Mercier was able to cultivate 
the rods and concludes that they are true bacteria and thinks 
them to be of a symbiotic nature although he was unable to 
suggest any advantage that the host receives because of their 
presence. They are given the name Bacillus cuenoti by Mercier. 
Many other investigators have reported bacteria within the 
eggs or tissues of insects. Blochmann (’87) observed them in 
Pieris, Musca, and Vespa; Stuhlmann (’86) shows them in many 
of his figures, and Forbes (’91) found them in the ecaecal glands 
of various Heteroptera. The ‘green or yellow granular mass’ 
described by Leydig (’50) in the embryos of viviparous aphids 
“and later called the ‘pseudovitellus’ by Huxley (’58) and the 
‘green body’ by Witlaczil (84) is considered now to be due to 
symbiotic organisms. Of particular importance are the con- 
tributions of Mercier (’07) on the cockroach and of Sule (06, 
10), Pierantoni (10), and Buchner (’12) on the Hemiptera. 
Buchner (’12) has given a full historical discussion of the subject 
