90 GUIDE TO THE STUDY 



that will be apparent when sections are studied, has even been 

 regarded by some authorities as of metozoan rather than proto- 

 zoan relationship. Practically nothing is known of the life 

 history. 



PRACTICAL WORK 



Sarcocystis miescheriana is commonly found in the muscles 

 of swine. Examine under pressure fragments of infected pork 



c/ Z i. Zm Ze Z f t.c iri 



~^fe •- a - ' A to 



*"••»*£ 



c/i"s/x c/i ' s/ob 



Fig. 29.- — Longitudinal section of a cyst of Sacrocystis tenella from the oesopha- 

 gus of a sheep. Cyst wall; Z.e., Z.m., Z.i., external, mid, and inner layers; 

 Z.f., fibrous zone; t.c, connective tissue; m., muscle; ch.sp. chambers filled with 

 spores; ch.spb., chambers with sporoblasts. (After Alexeieff.) 



and note the small, white, elongated cysts, or " Miescher's tubes," 

 measuring from 2 to 3 mm. Dissect out some of these cysts and, 

 crushing the thick enveloping membrane, note the numerous 

 sickle-shaped spores. 



Examine sections of muscle containing cysts of this species, 

 or of Sarcocystis tenella of the sheep. Selecting a well-developed 

 cyst, note that it is divided by membranous walls into a great 

 number of chambers. The more central of these are empty, but 

 the peripheral ones are filled with masses of the deep-staining, 

 thin-walled falciform spores. The most peripheral chambers 



