The Trichina Spiralis. 85 



part. This afterwards contracts, enclosing each worm in a 

 separate sac, which is finally in its turn enveloped by a 

 deposit of calcareous matter. The Trichina now remains 

 quiescent in his shell for an indefinite period of time, wait- 

 ing until some unfortunate animal shall receive him into 

 his stomach, when the acid contained in the gastric juice dis- 

 solves the walls of his prison house, and sets him free to 

 give birth to a new generation, who go through a similar 

 cycle of existence, while the parent worm dies and passes off" 

 with the intestinal evacuations. It follows from the above 

 observations that the Trichinae have four distinct phases 

 of existence: 



1st. The Trichina?, when swallowed, stop in the intes- 

 tine, complete their development there, give birth to young, 

 and then die. 



2d. The little Trichinae, as soon as born, migrate into 

 all the striated muscles, except those of the heart. 



3d. Haviug reached the muscular system they increase 

 in size but not in number. 



4th. They become encysted and remain quiescent until 

 eaten by man, or certain animals, when they in turn give 

 birth to a new generation, after which they die. 



The symptoms produced by this parasite vary according 

 to the number swallowed and to their different locations 

 in the body, and the disease called Trichinosis may 

 be divided into three stages: 1st. The period of a intes- 

 tinal irritation. 2d. The period of muscular irritation; and 

 3d. That of convalescence or termination. 



The severity of the symptoms of course vary greatly in 

 different cases. Sometimes the intestinal irritation is so 

 slight as to pass unnoticed by the patient, while, on the 

 contrary, it at other times results in diarrhoea with bloody 

 discharges, with severe abdominal pain, and more rarely in 

 constipation. The tongue is ordinarily dirty and coated. 

 There is nausea, with mucous or bilious vomiting, tumefac- 



