532 A MANUAL OF BACTERIOLOGY 



Nosema bombycis causes pebrine, a disease of silkworms, which 

 is of considerable importance commercially, for the silk industry 

 in France was once threatened with extinction owing to its ravages. 

 The infected worms do not grow normally, cease to eat, and die, or 

 may form abnormal pupse. Within the body of the affected worms 

 a large number of roundish, highly refractile corpuscles are found. 

 Pasteur ascertained that the disease was propagated by healthy 

 worms eating with their food the excreta of infected ones. The 

 moths were thus infected, and laid infected eggs. By allowing each 

 moth to lay its eggs separately, and subsequently examining the 

 body of the moth microscopically, he was able to separate the healthy 

 from the diseased, and the eggs of the former were kept, while those 

 of the latter were destroyed. According to Pfeiffer, 1 when the 

 worms eat the excreta containing the corpuscles mentioned above, 

 these lose their capsule and form large amoeboid masses which 

 penetrate the muscles and blood-corpuscles. The amoeboid masses 

 then become encapsuled and are yellow and granular. Later on 

 the bright roundish corpuscles form within them. 



The Isle of Wight bee disease is caused by Nosema apis, which 

 is mainly confined to the alimentary tract. 



Another disease of silkworms is known as flacherie, but is due 

 to a bacterium, Micrococcus bombycis. It is contagious, and can 

 be transmitted by inoculation. 



Order. Sarcosporidia 



The parasites belonging to this order are not thoroughly worked 

 out. They complete their life-history in the substance of striated 

 muscular fibres : such are the well-known Miescher's corpuscles. 

 Few instances of this class of parasite are recorded in man, but it 

 occurs in the monkey 2 and also in the ox. T. Smith 3 describes 

 the characters and development of a species found in mice. 



A parasite, Rhinosporidium kinealyi, nearly allied to the fore- 

 going, causes a polypoid condition in the nose in the tropics. If 

 a section be made of the mass, cysts (pansporoblasts) will be seen 

 in the deeper layers containing many refractile rounded nucleated 

 bodies, the spores. Neither the life-history nor the mode of trans- 

 mission of the parasite is known. 



1 Zeitschr.f. Hyg., vol. iii, 1888, p. 3. 



2 De Korte, Journ. of Hygiene, vol. v, 1905, p. 451 



3 Journ. Exper. Med., vol. vi, No. 1, 1901, p. 1. 



