TRICHINA SPIRALIS. 569 



spermatic cells are found, the sexes in the mean "while be- 

 coming distinctly marked. Shortly afterwards the ova are 

 impregnated, and young living entozoa are developed within 

 the bodies of the female. The young have been noticed 

 (by Virchow) under the form of minute Filarice, more 

 especially in the serous cavities, in the mesenteric glands, 

 &c. Continuing their migrations, they penetrate as 

 far as the interior of the primitive muscular fasciculi, 

 where they may be found as early even as three days 

 after ingestion, in considerable numbers, and so far deve- 

 loped that the young entozoa have almost attained a size 

 equal to that of the full-grown Trichinae. They pro- 

 gressively advance into the interior of the muscular fasci- 

 culi, where they are often seen several in a file one after 

 the other. Behind them the muscular tissue becomes 

 atrophied, and around them an irritation is set up, and 

 from the commencement of the third week they are found 

 encysted. The sarcolemma is now thickened, and the 

 contents of the muscular fibres exhibit indications of a 

 more active cell-growth ; the cyst is the product of a sort 

 of inflammatory irritation. 



Professor Virchow draws the following conclusions : — 

 " 1. The ingestion of pig's-flesh, fresh or badly dressed, 

 containing Trichinae, is attended with the greatest danger, 

 and may prove the proximate cause of death. 2. The 

 Trichinae maintain their living properties in decomposed 

 flesh ; they resist immersion in water for weeks together, 

 and when encysted may, without injury to their vitality, 

 be plunged in a sufficiently dilute solution of chromic acid 

 for at least ten days. 3. On the contrary, they perish and 

 are deprived of all noxious influence in ham which has 

 been well smoked, kept a sufficient length of time, and 

 then well boiled before it is consumed." 



The Echinococcus found in cysts, chiefly in the human 

 liver, is represented in Plate IV. No. 101. A large col- 

 lection was taken from the liver of a boy who died in 

 Charing-cross Hospital from accidental rupture of the 

 liver. The cysts containing these parasites are always 

 situated in cavities in the interior of the body. These 

 cavities may be situated in any part of the tissues or organs 

 of the body, but are more frequently found in the solid 



