ACTION or ANTHELMINTICS. 149 



the cysts which may be felt through the skin might be mistaken for 

 abscesses or other tumours. In many cases, however, a sufficient and 

 reliable diagnosis may be based on the manner of occurrence and dis- 

 •tribution, but only the results of excision and puncture can finally 

 establish the diagnosis, and this corroboration ought never to be dis- 

 pensed with if the detection of the evil is of any use, as, for example, 

 in the case of contemporaneously occurring mental diseases. 



Among the remaining parenchyma-worms it is sometimes possible 

 to distinguish Echinococcus, and that not only when, as occasionally 

 happens, it empties its contents through the lungs or kidneys, or the 

 alimentary canal, but also when it remains quiescent in the form of 

 a closed cyst. A diagnosis may then be established by means of 

 auscultation and percussion. We are thus not only informed of the 

 existence of an encysted tremulous swelling, but by means of the 

 so-called " hydatid sound " are enabled to identify it as a specific 

 formation, and to distinguish it from other dropsical swellings. 



CURE AND PREVENTION. 



After the detection of a parasitic disease there must follow, not 

 only a treatment of the various symptoms, but a realisation of the 

 indicaiio causalis ; that is to say, the removal of the parasites whose 

 presence has induced the pathological state. 



The means taken by the physician to attain this end will, of 

 course, vary greatly, according to circumstances, and will not in every 

 instance lead with equal ease to the desired result. In general, the 

 more accessible the organ which the parasite infests, the more hope- 

 fully may success be looked for. 



The simplest problem is evidently the removal of the Epizoa, 

 either directly by mechanical means, or, more thoroughly and con- 

 veniently, by killing them with suitable preparations (mercury, 

 ethereal oils, petroleum, &c.). In general, the inmates of the ali- 

 mentary canal stand next as regards facility of expulsion, although 

 the varied structure of the organs of attachment occasions consider- 

 able differences in matters of detail. These worms are treated with 

 the so-called " anthelmintics," in which our pharmacopaeia so richly 

 abounds. Their action is primarily directed either against the worms 

 themselves or upon the walls of the alimentary canal. The majority 

 of specific worm-cures belong to the first class. They operate by 

 killing or stupefying, or in some way unpleasantly affecting, the 

 worms, so as to induce them to wander outwards, while the second 

 class are successful by increasing the peristaltic movements, or by 



altering the secretions. 



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