TRICHINA SPIRALIS. 335 



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



from Trichinae, 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 



clyscrasia 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, 



arid 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 hooklets, and 



then pierce directly through the articulating membrane of the 



tarsi of the larvee 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 walls 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 Trichinae. 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 



