TBIOHINA SPIRALIS. 341 



cauglit the little larva3 in the very act of passing into and ont of the 

 abdominal cavity, and also within various parenchymatous tissues 

 on their way to the more superficial and remote parts of the body. In 

 one of Yirchow's earlier experiments, he found the wandering larv^ 

 in the mesenteric glands, as well as in the cavities of the peritoneum 

 and pericardium. The heart itself has occasionally been selected 

 as a permanent resting-place ; at least, Yirchow saw this in one 

 instance. After the brood has migrated to the territory destined 

 for its temporary sojourn, the voluntary muscles undergo a process 

 of degeneration, the various stages of which have been beautifully 

 illustrated by Leuckart, in his monograph ; but the point, which I 

 am more concerned to notice, is the fact that, whilst in the adult con- 

 dition. Trichinae will perish only a few days subsequent to the decease 

 of the host in which they happen to dwell, they are, on the other 

 hand, in the larval state, capable of retaining their vitality long after 

 the death of the bearer. M. Davaine kept the larv^ alive in water 

 for a month, but the adult worms perished in cold water in about 

 an hour. Under ordinary circumstances, Davaine' s observations 

 lead us to conclude that the adult worms do not survive their hosts 

 above six hours ; but the larvae will live for a long time in flesh 

 which has already undergone putrefaction. In this way, as Davaine 

 very naturally suggests, " the debris of an animal devoured by 

 carnivora may become fatal to rodents, or a carcase near a marsh 

 or rivulet may communicate the parasites to the ruminants which 

 drink the water, or to pigs ;" for, it is within these last-named 

 bearers that the Trichinae seem most liable to take up their abode. 

 From what has now been advanced, it is easy to understand how 

 we om-selves become infected with Trichinae, and therefore subject 

 to the febrile helminthic disorder termed Trichiniasis ; but, before 

 I adduce evidence as to the formidable nature of this malady, it will 

 be well to give a general summary of the facts above recorded, 

 in addition to one or two others which have been purposely omitted. 

 In my paper communicated to the Zoological Society, I have made 

 a brief resume of this kind, based chiefly on the writings of Virchow, 



