148 THE EFFECTS OF PARASITES ON THEIR HOSTS. 



arise from an accidental rupture of the joint, often readily consequent 

 on the contraction of a distended uterus. One does not expect to find 

 eggs of TrichincB on such examination, since, as is well known, the 

 embryos of these worms become free within the body of the parent, 

 and immediately bore through the walls of the intestine. But, on the 

 other hand, one sometimes finds the n\o\Aie,\-Trichince themselves, 

 though on the whole much less frequently than, judging from the 

 analogy of Ithahditis stercoralis, one would expect from their usually 

 very abundant occurrence in the alimentary canal of the host. To 

 understand this we must remember that the Trichince are enabled by 

 their long, thin form to adhere closely to the intestinal villi, and, thus 

 protected, to escape the pressure of the faeces. 



Balantidium (Paramcecium) coli is, like Rhahditis stercoralis, also 

 to be found in great abundance in the fseces and intestinal mucus both 

 of man and of the pig. In similar fashion evidently we may expect 

 to diagnose Strongylus gigas, Filaria sanguinis, and Distomum hoema- 

 tdbium from the urinary deposits, the species of Strongylus infesting 

 the air passages from the sputum, and Fentastonium tcenioides from 

 the nasal mucus ; and all this has been at least partially established 

 by experiment. 



The inmates of the various organs which open to the exterior are 

 not, however, the only parasites whose presence admits of objective 

 proof. Thus by the simple examination of the tongue, especially of 

 the under surface, it is sometimes possible to aiBrm the presence both 

 of Trichince ^ and of Cysticercus.^ Similarly we can, by the use of the 

 opthalmoscope, not only recognise the same inmates in the eye, but 

 determine their position with the greatest accuracy. ^ When the sus- 

 picion of trichinosis is not fully confirmed by the usual methods, we 

 have only to remove a small piece of flesh from the deltoid, or from 

 any other easily accessible muscle, and subject it to microscopic ex- 

 amination. 



Filaria Medinensis presents no peculiar difficulty in diagnosis, 

 especially in the later stages, when the head of the worm has bored 

 through the skin, and when the living brood passes to the exterior 

 along with the secretion of the perforated part. The diagnosis of 

 Cysticerus in the intermuscular connective tissue is less certain, for 



^ This is only possible when the Tric?iina-ca.psn\es are already calcified— that is to say, 

 when the infection had occurred some considerable time previously. 



^ Even Aristotle recommends the examination of the tongue in pigs for the diagnosis 

 of bladder-worm disease (" Hist, anim.," lib. viii., cap. 21, N. 3, " A^Xai S'eMv al xaXofwtrai- 

 ly T€ yap ttjs y\iliTTT]s ti}, Karifi, l^o'"''' MttXitrra ras x^^'fjos." 



" See especially the observations of v. Grafle, Journal/. Opiuhalmologie, p. 308, 1857. 

 According to a later report ( Verhandl. d. med. Gesellsch. Berlin, p. 96, 1871), v. Grafife 

 has observed more than a hundred cases of bladder-worm in the eye. 



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