754 OKDER: MICROSPORIDIIDA 



spores are reniform, and measure 3 to 4 by 1-5 to 1-8 microns. The 

 polar filament is 45 to 55 microns in length. The pansporoblast gives rise 

 to eight sporoblasts, which become eight spores. 



Supposed Microsporidiida in Rabies and Encephalitis of Rabbits 

 and Mice. 



Wright and Craigliead (1922) observed a form of paralysis in young rabbits, 

 and found that it was due to an organism which they thought might be a Protozoou. 

 It was found in most of the tissues of the body, but was specially noticed in the 

 kidneys and urine and in nerve cells of the spinal cord, which were quickly destroyed 





a 



Fig. 322. — Encephalitozoon cuniculi in Section of Brain of Rabbit (x950). 

 (After Da Fano, 1924, from Journ. Path, and Bad.) 

 Parasites in cysts which may be merely vacuoles in macrophages. 



by its presence. The same disease of rabbits had been observed by Bull (1917), 

 Oliver (1922), and Twort (1922). They described the changes in the nervous system 

 without associating them with any particular organism. In attempts to reproduce 

 human diseases, encephalitis lethargica and herpes, in rabbits, the naturally occurring 

 disease of rabbits and the associated organism have given rise to some confusion. 

 Doerr and Zdansky (1923) described the lesions in the brains of rabbits inoculated 

 with the virus of encephalitis lethargica, and discovered that similar lesions occurred 

 in uninoculated animals. They saw in the brain certain small bodies which they 

 thought were probably parasites resi)onsible for a disease of rabbits which was being 



