06 DISEASES OF MUSCLES AND TENDONS. 



abdominal pain in the form of dull colic, and sometimes irritation of the 

 peritonemn. The embryos carried by the circulation then escape into 

 the tissues and, like the cysticerci, become encysted, preferably in the 

 muscles, in the interfascicular connective tissue towards the ends of the 

 bundles. Each (asexual) parasite plays the part of a foreign body, 

 causing infiltration of serum and exudation of leucocytes in its neighbour- 

 hood, and soon becoming encysted in the interior of a little ovoid space 

 surrounded by a fibro-fatty wall. Fat granules accumulate at each end 

 of the cyst. 



The parasite, which at first appeared straight, soon assumes a bent 

 form, then that of a figure " 6," then of a figure *' 3," and preserves a 



Fig. 47. — Free larval 

 trichina. (Colin.) 



Fig. 48. — Trichinae encys- 

 ted in the muscular 

 tissue. (Colin.) 



Fig. 49.— Old (degene- 

 rated) trichina cyst. 

 (Colin.) 



latent vitality throughout the entire period of encystment. These cysts 

 are of very small dimensions, invisible to the naked eye, and their 

 discovery necessitates the use of the microscope. They are about ^yh 

 inch in length and ^-Joth inch in width. Very frequently two or three 

 cysts may be found arranged in line, presenting the appearance of 

 beads on a string : more rarely two parasites may be found in one cyst ; 

 exceptionally, as many as six or seven. The appearance of " beads on a 

 string " is due to the fact that the parasites follow the interfascicular 

 capillaries. 



In animals which are kept for a long time and fattened the cyst walls 



