SPOROZOA 



431 



Nosema Bombycis. This organism was discovered by Naegeli 

 in 1857. It is an example of the Neosporidia and is of peculiar 

 interest as the cause of pebrine, the disease of silkworms studied 

 by Pasteur in 1866-1870, and largely eradicated by application 

 of the methods devised by him as a result of his investigations. 



FIG. 206. Gregarina blattarium. I, Two individuals stuck together. //, Cysts 

 with conjugated cells and developing spores. Ill A, Unripe spore with undivided 

 contents. IIIB, Ripe spore with eight sporozoits; ek, ectoplasm; en, endoplasm; 

 cu, cuticula; pm, protomerit; dm, deuteromerit; n, nucleus; pn, spores; rk, residual 

 body; sk, sporozoits. (From Doflein after R. Hertwig.) 



The spore of N. bombycis is 1.5 to 2/z wide by 3/1 long. If treated 

 with nitric acid it swells and reaches a length of 6/* and extends 

 a slender thread which may be lo/x long. The spore is ingested 

 by the silkworm and in its intestine the ameboid parasite es- 

 capes and penetrates the epithelium. It may pass to any part 

 of the host to undergo its further development. Multiplication 



