TRICHINA SPIRALIS. 337 



with a capsule and cyst in which the worm increases in size to a 

 certain extent, and besides the intestinal canal, developcs the 

 primitive foundations of an organ which we shall hereafter find 

 to belong to the generative apparatus. In this case also no 

 orgau of the worm is cast off in the metamorphosis, as is the 

 case, for example, in the Cercarice. The structure of the en- 

 veloping membranes of the young Trichinae which occur in the 

 muscles of the human subject has not yet been observed, but 

 from what Meissner says on this subject and what we know of 

 the Cestoidea, we may certainly draw some definite conclusions. 

 The immigration itself will hardly take place without inflammation 

 of the tissues passed through, to which the human organism 

 answers by exudation, which also furnishes the material for the 

 capsule enveloping the Trichina, of which, making use of 

 Luschka, we give the following description : 



The cyst, which varies greatly in dimensions (on an average 

 0*32 mill, in length and 0*038 mill, in transverse diameter), is 

 sometimes oval, sometimes circular, sometimes exhibiting elon- 

 gated extremities on both sides, sometimes only at one end. In 

 Luschka's case the latter formations were extremely rare, and the 

 oval forms were the most common ; by other authors, those with 

 a process on one side are said to be the more ordinary forms, 

 and these were also the most abundant in the case observed by 

 Zenker, and presented to me to make use of, and indeed so 

 abundant, that Zenker in sending me the fresh muscle with 

 Trichina, called my attention at once to this variation from 

 Luschka's observation. Besides the forms with a process on one 

 side, I also had the opportunity of detecting processes on both 

 sides. Luschka very rarely found tubular or gourd-like cysts. 



According to the time which has elapsed since the immigration, 

 the cysts are sometimes transparent and sometimes opaque, and 

 then white by reflected and dark by transmitted light, rich in 

 sharply defined, larger and smaller elementary granules, which 

 are placed more or less close together, always less close towards 

 the periphery (leaving lighter spots and a lighter periphery 

 of 0024 mill, in breadth), and which give the capsule a tole- 

 rably rigid texture, so that it grates when cut. These struc- 

 tures, which imitate the form of the elementary granules, are 

 probably nothing but carbonate of lime, or lime salts combined 

 with an organic substance. That this deposition of lime salts in 

 the walls of the cysts increases with the time which has elapsed 



Y 



