TRICHINOUS INFECTION OF MAN AND ANIMALS. 165 



cation of naturalists to the order of nematoid worms. Yet he was 

 unable to decide which was the anterior extremit}', and for nearly 

 fifteen years there was no advance of anatomical knowledge on the 

 subject. 



It therefore remained for Prof. H. Luschka of Tubingen Univer- 

 sity, in 1850, to point out more accurateh' the internal structure. 

 He carefully traced the digestive canal, discovered the sexual organs 

 of the female, and conclusively proved that the mouth was situated 

 in the pointed end of the worm, and not in the blunt extremity, as 

 was generally believed. He described the cyst in its advanced stages, 

 and demonstrated for the first time a complicated system of blood 

 vessels, and an external membrane of connective tissue by which it 

 is surrounded. In his observations on the vitality of the trichinae, he 

 found that they survived putrefaction and freezing of the muscles. 



Dr. Herbst, a German helminthologist, followed in this line of in- 

 vestigation, and his experiments on dogs actually solved the question 

 concerning the propagation of trichinae. He was the first to rear 

 encapsuled flesh-worms in the muscular tissue, and claimed that in 

 this state only the}' were transferable from one animal to another. 



Dr. Kuchenmeister, having previously shown the transformation 

 of measles or hydatid taeniae into tape worms, was led to the suppo- 

 sition that the trichina might be a juvenile form of a known nema- 

 tode ; and after a series of observations, he declared that this 

 flesh- worm was the larva of the TricJiocephalus dispar."*^ 



A new impulse, however, was given to trichinal investigation in 

 1859, b}' Prof. Virchow'sf experiments. He fed a dog upon tri- 

 chinous meat, and in four days found a large number of these nema- 

 todes fully developed and sexually mature in the intestines, but he 

 failed to observe the migration of the new-born worms which Herbst 

 had previously demonstrated. This was owing partiall}' to his hav- 

 ing killed the dog too early, and also from the fact that he selected 

 an old animal for the experiment, through whose firm tissues the 

 young trichinae scarcely ever penetrate. 



Prof. R. Leuckart,J of Giessen, followed up the researches on the 

 embr3'ology of the parasite ; he made a series of experiments on 

 trichinal infection that were ver}' comprehensive, and did much to 



*Aniraal and Vegetable Parasites, Sydenham Ed., 1857, Vol. I,.page •221. 

 tCyclopedia of Anatomy and Physiology, Vol. II, page 126. 



JFor a summary of his views see Burk's translation in Quar. Jour, oi Microscopical Sci- 

 ence, Vol. VIII, page 168. 



