SARCOSPORIDIA 579 



are seen. The latter subsequently divides the cytoplasm segments, 

 and in this manner the balls become sporoblasts and their contents 

 are transformed into numerous crowded, curved, oval, sickle- or 

 crescent-shaped spores. It is not known how the sarcosporidia first 

 gain entrance into animals, nor is their life cycle well known. It is 

 believed that part of it occurs in an intermediate host, and it has been 

 claimed that mollusks (snails) play this role. Sarcosporidium infection 

 in animals is, as a rule, a harmless process. The parasites, however, 

 may be very numerous throughout the entire muscular system, and 

 may so interfere with its nutrition and function; or the sacs may be 

 in locations where they may do harm. The giant sarcosporidia in 

 the esophagus of the sheep, for example, may interfere with deglu- 

 tition and respiration. A few cases of sarcosporidia infection of 

 the laryngeal muscles of horses have been reported; the author has 

 seen such a case in which the larynx became the seat of considerable 

 inflammatory infiltration, with respiratory disturbances. Sarco- 

 sporidia can be studied from fresh material, unstained and also in 

 stained sections of infected muscles. 



Sarcocystis miescheriana is the sarcosporidium most commonly 

 found in hogs. The sacs are from 0.5 to 4 mm. long and 3 mm. wide. 

 The pansporoblasts (the balls which subsequently develop the spores 

 in their interior) are 5 to 6 micra in diameter. If pork is extensively 

 infected by these sarcosporidia it is "off color," yellowish or grayish 

 red. The sacs often show the evidences of leukocytic infiltration 

 and of calcareous degeneration. 



Sarcocystis bertrami, generally 9 to 12 mm. long, is found in the 

 muscles of the horse. It may cause interstitial myositis, and may 

 become dangerous when located in the muscles of the larynx. It 

 sometimes affects the muscles of the hind leg of young horses and 

 causes lameness. 



Sarcocystis tenella infects the muscles of sheep and goats. The 

 organism varies considerably in length, namely, from 40 micra to 

 2 cm. The sac membrane is very delicate in young parasites, but 

 becomes thick and tough when they grow older. The large cysts 

 contain a layer of sporoblasts along the interior of the membrane, 

 but the centre is composed of an empty meshwork only. The spores 

 are first perfectly round, but small and kidney-shaped after their 

 full development. This sarcosporidium invades many of the muscles 

 of sheep and goats, and also the heart muscle and its endocardium. 



Sarcocystis lindemann has been found by R. Koch and by Kartulis 

 in Africa in the muscles of man and also by others a few times in 

 other parts of the world. 



Balbiana rileyi, another sarcosporidium, was found by Stiles in 

 the muscles of ducks in the United States. 



