NEMATODA 



155 



trusion of the parasite the infested muscular fibre loses its 

 original structure, the fibrillae collapse into a finely granular 

 substance, whilst the muscular corpuscles change into oval 

 nucleated cells. (10) The infected muscular bundle retains 

 its original sheathing up to the time of the complete develop- 

 meut of the young Trichinae, but afterwards its sarcolemma 

 thickens, and begins to shrivel at the extremities. 11. The 

 spot inhabited by the rolled-up parasites is converted into a 

 spindle-shaped widening, and within this space, under the 

 thickened sarcolemma, the formation of the well-known lemon- 

 shaped or globular cysts commences by a peripheric hardening 

 and calcification. This degeneration commences several months 

 after the wandering. Immature muscle - Trichinae are not 

 capable of producing 

 infection. (12) The 

 migration and deve- 

 lopment of the em- 

 bryos also take place 

 after the transporta- 

 tion of impregnated 

 Trichinae into the in- 

 testines of a new 

 host. (13) The fur- 

 ther development of 

 the muscle-Trichinae 

 into adult animals is 

 altogether indepen- 

 dent of the forma- 

 tion of the calcareous 

 shell, and occurs as soon as the former have reached their 

 completion. (14) Males and females are already recog- 

 nisable in their larval state. (15) The immigration of the 

 Trichina-brood in masses produces very grave or even fatal 

 consequences, such as peritonitis (from the embryos perforat- 

 ing the intestinal walls), pain, and paralysis (resulting from the 

 destructionof the infected muscular fibres). (16) The infection 

 of man occurs especially through swine. (17) The^ muscle -Tri- 

 chinae are so capable of resistance that they are by no means 

 in all cases destroyed by the ordinary methods of roasting, 

 cooking, pickling and smoking. (18) As a rule, swine obtain 

 Trichinae from rats, to which latter we also as the natural 

 bearers have to convey them. Microscopic examination of 



FIG. 37. Immature female Trichina from muscle. 

 After Leuckart. 



