PARASITOLOGY. 155 



may appear nearly round ; the long- axis is parallel 

 with the muscle fiber ; the cyst usually contains only 

 one larva although as many as seven have been ob- 

 served ; in this cyst the parasite remains dormant until 

 the animal is killed and the meat is eaten, or if not 

 slaughtered for several months the cyst will undergo 

 degeneration. Two kinds of degeneration are noted, 

 fatty and calcareous ; in a few months the cysts are 

 usually observed to commence fatty degeneration; 

 first there are noted a few fat globules at the polls ; 

 these gradually increase and the fat is set free and 

 invades the whole cyst ; at about the seventh month 

 lime salts (carbonate and phosphate) begin to ap- 

 pear; calcification is usually complete about the 

 twentieth month; during this process the cyst gradu- 

 ally becomes opaque until the outline of the larva 

 can scarcely be seen. Birds prove unfavorable sub- 

 jects for muscular trichinosis; they, however, de- 

 velop the intestinal form. 



Animals Infested, — Man, hog, dog, rat and, experi- 

 mentally, other animals. 



Parts Infested. — Adults infests the intestine ; the 

 larval form infests the muscle structures. 



Conditions Produced. — This parasite produces two 

 form of trichinosis ; the adult infests the intestinal 

 tract and produces intestinal trichinosis ; the worm 

 lives about six weeks ; the larva is found wandering 

 in the tissues and, finally encysted, this form is 

 muscular trichinosis. 



Symptoms. — Man : — Nausea, vomiting, diarrhoea 

 and vertigo ; elevation of temperature with acceler- 

 ated pulse and respiration; great muscular pain dur- 

 ing migration of the embryos ; contraction of certain 



