426 THE ANIMAL PARASITES OF MAN 



sarcolemma is glassy and thickened. The inflammation also extends 

 to contiguous fibres, especially to the intramuscular tissue, which 

 proliferates greatly, especially in the vicinity of the degenerated fibres. 

 While the latter become more and more absorbed, the capsule is 

 formed by the inflamed connective tissue, which, penetrating into the 

 glassy and thickened sarcolemma from the poles of the spindle, forms 

 the cystic membrane. According to other authorities, the larvae settle 

 in the ////miiuscular connective tissue which forms the cyst and not 

 in the muscular fibres within the sarcolemma. The cysts are lemon- 

 shaped and usually lie with their longitudinal axis in the direction of 

 the muscular fibres ; on an average they measure 400 /JL in length by 

 250 //, in breadth. 



Later on fat cells appear at their poles, and after about six or 

 nine months they commence to calcify, the process starting at the 



FlG. 305. Various phases of the calcification of 

 Trichinella of the muscles, which starts at the poles 



FIG. 304. Calcified Trichinella in the of the ca P sule - 

 muscular system of a pig ; the capsules are 

 not calcified. (After Ostertag.) 



poles (fig. 305). Finally, sometimes after the lapse of years, the 

 captive Trichinellae themselves become calcified. 



According to experience, Trichinellae are not evenly distributed 

 in the muscular system of pigs ; the diaphragm, the muscles of the 

 larynx, tongue, abdomen and intercostal spaces are their favourite 

 positions ; this predilection for the respiratory muscles is explained 

 by their regular contractions, owing to which regular narrowings 

 of the capillaries take place, thus favouring the settling of the cir- 

 culating Trichinellae. The same circumstance probably explains the 

 frequency of the parasites in the tongue. 



Possibly also the Trichinellae that bore direct through the intestine 

 may, from the abdominal cavity, penetrate the muscles in the vicinity. 

 Frequently also encysted Trichinellae are found in remarkable numbers 



