334 ENTOZOA. 



CHAPTEE XII. 



TRICHINA SPIRALIS. 



General and specific characters of Trichina spiralis — Historical notice — Our knowledge 

 of the structure, migrations, and development of Trichina, as gathered from the 

 investigations of Owen, Bristowe and Rainey, Virchow, Leuckart, and Davaine— 

 Medical importance of the subject — The flesh-worm epidemic, or so-called Trichi- 

 niasis^Cause of its prevalence in particular localities — Gamgee's practical observa- 

 tions — Value of the experimental method of research. 



At tlie close of the last chapter, under two separate headings, I 

 described certain larval nematodes which, after all, may possibly 

 be referable, not to two, but to three or even more species of worm 

 whose appropriate adult forms remain, at present, only a matter of 

 conjecture ; but, be that as it may, I come now to speak of a parasite 

 whose history, structure, development, migrations, embryonic and 

 adult conditions are all thoroughly well known. 1 need hardly 

 add, also, that the worm in question possesses an unusual amount of 

 interest, alike for the professional reader and the lover of natural 

 history science, especially if they be inclined to view the animal in 

 its various economical bearings. With the aid of Leuckart's exhaus- 

 tive memoir* it would not be difficult, indeed, to devote a chapter or 

 two to the experimental details on which our intimate knowledge 

 of the habits of the Trichina spiralis depends; but besides his 

 researches we have the earher though less comprehensive investiga- 

 tions of Virchow and Herbst, and the later, but equally interesting 

 and independent, observations of Davaine. 



* " Untersuchungen iibcr Trichina spiralis ; zugleioh ein bcitrag zur kenntniss der 

 Wurmkrankheiten." 1860. 



