CHAPTER LVI. 



Section I. The Microsporidia. 



1. Nosema bombycis, p. 752. 2. Nosema apis, p. 753. 

 Section II. The Myxosporidia, p. 754. 

 Section III. The Sarcosporidia, p. 756. 

 Section IV. The Haplosporidia, p. 759. 



SECTION I. THE MICROSPORIDIA. 



No Microsporidium is known to infect man but one species, Nosema bombycis, 

 is the cause of the silkworm disease known as pebrine and another species, 

 Nosema apis, is the cause of Microsporidiosis of bees the " Isle of Wight 

 disease." 



1. Nosema bombycis. 

 Synonyms. Microsporidium bombycis : [Glugea bombycis]. 



Cornalia was the first to observe the presence of bright oval corpuscles in 

 silkworms affected with pebrine. These corpuscles commonly described as 

 the corpuscles of Cornalia and which have obtained so considerable a notoriety 

 since the investigations of Pasteur and Balbiani represent a stage in the 

 life history of the parasite which is the cause of the disease. 



The spore of Nosema bombycis is a small oval or pyriform-shaped parasite 

 measuring 4 x 2/* surrounded by a spore-membrane and containing at one 

 end a single polar capsule in which is hidden a spirally-twisted filament which 

 can only with difficulty be demonstrated (Thelohan). 



For the purpose of studying the development of Microsporidium bombycis Balbiani 

 suggests the following experiment : Feed a number of young silkworms not more 

 than a few mm. long on mulberry leaves which have been washed over with an 

 emulsion made by rubbing up an infected silkworm moth with a little water. In a 

 few days the silkworms will be infected and the spores will be scattered along the 

 lumen of the alimentary canal. The spores make their way into the wall of the gut 

 and give origin to small trophozoites of variable size elongated in the direction of 

 the longitudinal muscular coat. 



Life history. [The development of Nosema bombycis l in the silkworm begins as 

 small uninucleate amcebulse which are in the first instance found free in the digestive 

 tract and later in the lymph channels. The amcebulse multiply by fission, wander 

 all over the body (planonts) and penetrate cells where they grow, assume an oval 

 or spherical form and become meronts or schizonts. The meronts multiply by 

 binary or multiple fission until they have filled and exhausted the host cell. They 

 do not however pass to other cells. The multiplication of the meronts may be 

 very similar in appearance to yeast cells and give rise to chains of cells. When 

 the host cell is used up the meronts do not multiply further but produce a final 

 generation of uninucleate cells which as sporonts give rise to a single^ spore. 



t 1 Vide Minchin, E. A. An Introduction to the Study of the Protozoa. London, 1912.] 



