CHAPTER XXVI 



SUBCLASS 3 ACNIDOSPORIDIA CEPEDE 



THE SPOROZOA which are provisionally grouped here are 

 mostly incompletely known, although some of them are 

 widely distributed among the higher vertebrates. They possess 

 spores which are quite simple in their structure, while their de- 

 velopment is so far as is known wholly different from that of the 

 Telosporidia. Two orders make up the subclass. 



Muscle parasites of higher vertebrates Order 1 Sarcosporidia 



Parasites of invertebrates and fish Order 2 Haplosporidia 



ORDER 1 SARCOSPORIDIA BALBIANI 



These Sporozoa are characteristic muscle parasites of mam- 

 mals, although reptiles and birds have also been found to 

 harbor them. The spore which has been known as "Rainey's 



Fig. 140 a. Sarcocystis tenella in the wall of oesophagus of sheep. 



b. S. miescheriana in the muscle of pig. Both natural size. 

 (After Schneidemiihl from Doflein). 



corpuscle," is crescent-shaped. One end is rounded and the 

 other pointed. Near the former end there is a single nucleus, and 

 the cytoplasm contains numerous granules. Infection of a new 

 host begins with the entrance of spore into the digestive tract 

 of a specific animal through the mouth. The delicate spore mem- 

 brane ruptures and the sporozoite is liberated, which enters the 

 gut-epithelium. After multiplying in this situation, the organism 

 makes its way into the muscular tissue. At the beginning the 



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