424 Veterinary Medicine. 



days after ingestion of the meat (Colberg, Hun, Neumann"). 



They may be found in the d iaphragm by the seventh day, and in 



the muscles generally by the thirteenth (Pagenstecher). Manj' 



are early found in the peritoneal and other serous cavities. 



f The number of young produced by a single female is estimated 



'by Neumann at 10,000 to 15,000, in a series of births of 1,200 at 



a time. This serves to explain the millions of muscle trichinae 



which come from the ingestion of a very small amount of trichi- 



\ nous flesh. 



On reaching the muscular or other tissue in which they are to 

 be encysted, the young worms are at first seen free in the connec- 

 tive tissue spaces, straight or perhaps slightly sinuous. Soon they 

 curl into a figure of 8, and later usually assume a spiral form. 

 In the interfascicular connective tissue the trichina causes irrita- 

 tion, inflammation, exudation, cell-proliferation, and finally or- 

 ganization into a homogeneous transparent ovoid cyst, with more 

 or less granular matter. Most commonly the trichina penetrates 

 the sarcolemma and develops within it displacing and causing 

 absorption of the primitive muscular fibres. The cyst is about 

 0.4 mm. long, by 0.25 mm. broad, the prolongation at the poles 

 varying so that it has sometimes a fusiform and sometimes a 

 pyriform outline. If treated with picrocarmine the cyst absorbs 

 mainly the picric acid and stands out yellow amid the surround- 

 ing rosy-red of the muscle. If injected the cyst is seen to be en- 

 veloped in a close capillary network. 



Trichina cysts are also found in the adipose tissue and in the 

 intestinal walls. 



Once encysted the larval worm is incapable of further develop- 

 ment, until its host is eaten by an animal in which it can develop. 

 If this is long delayed the worm perishes, the nutrition of the 

 cyst ceases, and it undergoes fatty or calcic degeneration. In the 

 latter case the muscle in the cadaver appears, marked by numer- 

 ous minute white spots as if it had been sprinkled with flour. 

 The calcareous matter (carbonate and phosphate of lime) can be 

 dissolved out by acids, but no distinct trace of the worm remains. 



If the infested muscle with the trichina cysts, recent and unde- 

 generated, is eaten by a suitable host, the muscle and cysts are 

 digested and the worms set free, to reach maturity and reproduce 

 their kind as already described. 



