TRICHINA SPIRALIS. 335 



case, for instance, even the muscle of the heart, which was free 

 from Trichina, was tender and exhibited fatty degeneration, and 

 in other muscles also entire moniliform longitudinal series of 

 fatty vesicles were deposited. Such phenomena are to be 

 ascribed to accompanying diseases, as in Luschka's case to 

 dyscrasia alcoholica, and at present we do not know at all whether 

 any particular texture of the muscles preeminently disposes them 

 for the flourishing of Trichina. The development itself may be 

 as follows : When a human being swallows in any way the 

 eggs or the youngest brood developed into ready-formed embryos 

 which occur in the eggs, or perhaps also when any female 

 Trichocephali residing in the small intestine of a man scatter 

 their eggs with the ready-formed embryos in them, which may 

 not be of very rare occurrence, within the human small intestine, 

 and also probably as far as the stomach, and when in either 

 case the egg-shells are burst and the embryos set free in 

 the intestinal canal, the desire of migration proper to them 

 awakens in them, and they set out, like the embryos of many 

 other Nematoida, in the shortest and easiest way towards the part 

 of the tissues which they particularly prefer as their dwelling 

 place. Whilst the brood of the Gordiacea, which are deposited 

 in the water, free themselves from their egg-shells, according to 

 Meissner, by boring through it with their twelve booklets, and 

 then pierce directly through the articulating membrane of the 

 tarsi of the larvae of Ephemera during the night into the feet of 

 the latter, and then advance between the primitive fasciculi of 

 the muscles through the foot into the body ; in the case of those 

 young round worms, whose brood is neither deposited in the 

 water nor escapes there, but which reach the intestinal canal in 

 the interior of their egg-shells, the bursting of the latter may take 

 place with the assistance of the digestive process, and then the 

 migration may go on through the thin Avails of the intestinal 

 canal, and they further advance in the body, by pushing forward 

 between the displaced muscular fibres. That in this case, as in 

 that of the Cestodea, the intestinal canal may furnish a point ot 

 immigration from the exterior, is best shown by the fact that the 

 muscles of the tongue, pharynx, and oesophagus, as well as the 

 Sphincter ani internus, are visited by the Trichince. In some cases 

 also the blood may be the bearer of the migrating brood. Meissner 

 not unfrequently found the young within the blood-vascular 

 system, and, for example, often attached to the inner walls of the 



