TBICHINA SPIRALIS. 333 



originally the dog in my eye, but perhaps wrongly, as this animal 

 appears to be better adapted to further the development of 

 certain further advanced, encysted, but still immature entozoa in 

 his intestine, than to produce the encysted forms from the 

 embryos which have migrated through the walls of his intestinal 

 canal. I advise any one who may have the means for this expe- 

 riment at command, to make it upon sheep, rabbits, or, above all, 

 upon pigs. For without at all believing that all the hitherto dis- 

 covered, encysted, immature nematode worms belong to one and 

 the same species, I think that Diesing's Trichina affinis, which 

 Leidy found in Philadelphia in the extensors of the thighs of a 

 pig, and which can scarcely be said to be larger, may be identical 

 with our T. spiralis. For this reason, therefore, I advise the 

 administration of the eggs of Trichocephalus dispar to the pig, 

 which is moreover the victim of a Trichocephalus within its 

 intestine, which we know as T. affinis, and which is regarded by 

 many as identical with T. dispar. 



This last announcement of the occurrence of Trichina 

 affinis in the flesh of the pig, however, gives us a hint as 

 to how man may possibly infect himself with Trichocephalus 

 dispar. This would take place in the same way as we 

 have described under Taenia solium ; that is to say, by the 

 consumption of pork which is beset with Trichina. Upon 

 the unsuccessful experiments in the administration of the true 

 Trichina spiralis to dogs, the reader may consult the following 

 remarks. 



Trichina spiralis,Owen andLuschka, as the brood of Trichocephalus 

 dispar engaged in migration. (PI. VII, figs. 5 8.) 



This asexual worm, first described by Owen in 1835, was 

 first seen, according to Diesing, by Tiedemann in the year 1822, 

 at least he first found the cysts of the worm. Subsequently, 

 the worm was seen by Hilton and Wormald in 1833, by 

 Paget and Knox, and also by Kobelt and BischofF in 1841, and 

 in Denmark by Monster and Svitzer in 1843. In Germany 

 it has been seen and described repeatedly. But, nevertheless, 

 the descriptions of the worm have been very imperfect, until that 

 given by Luschka and Herbst in 1851. Luschka's anatomical 



