ENTOZOA IN THE MUSCULAR SYSTEM. 203 



is composed of two distinct vesicles, an external one, 

 which gives it its fusiform appearance, and wliich 

 constitutes the prolongations at either end, and an 

 internal one, which is usually oval, and is not elon- 

 gated at the extremities like the outer vesicle. 



Numerous opinions have been advanced respecting 

 the nature of these vesicles. Professor Owen says 

 that they are homogeneous, and are constituted by 

 layers of condensed areolar tissue, which he con- 

 siders to be produced from the human tissues ; 

 other observers state that the two vesicles have a 

 different structure ; whilst others, again, including 

 Dr. Bristowe and Mr. Rainey, believe that the cyst is 

 single, and is exclusively the product of the trichina. 



The walls of the cyst abound in numerous ele- 

 mentary granules of an earthy character. Its cavity 

 contains a substance which is frequently opaque, and 

 consists of refractive globules, of different sizes, sus- 

 pended in a viscid fluid ; no cells, nor nuclei have 

 ever been observed in this substance, in which the 

 entozoon is, as it were, embedded. 



Trichinee are not found in all of the cysts, and 

 those which do exist are in a condition of develop- 

 ment, or of alteration, or are completely modified in 

 their characteristics and destroyed. The death of a 

 trichina is followed by the deposition of earthy 

 matter, chiefly composed of carbonate of lime, in the 

 body of the worm and the surrounding space. 



Trichinae have been observed in nearly all of the 

 muscles which possess striated fibres, with the excep- 

 tion of the heart. The number of these parasites is 

 most extraordinary in some cases ; and they have 

 been known to be so universally disseminated 



