150 THE EFFECTS OF PARASITES ON THEIR HOSTS. 



We restrict ourselves here to mere hints, for our knowledge of the 

 real nature of the operations of these anthelmintic remedies is still 

 uncertain and fragmentary. The experiments of Kiichenmeister who 

 (following Eedi's example) brought Ascaris and other intestinal worms 

 into direct contact with certain substances have done, as yet, but 

 little to enlighten us upon this dark subject, though they deserve full 

 recognition as the first attempts made to settle the question in a 

 rational manner. 



In the other vegetative organs, worms can generally be treated 

 only indirectly, by applications which increase the functional activity 

 of the structure affected, and especially increase its secretions. Suc- 

 cess can only be doubtful, though the hope is that the worms will be 

 carried to the exterior with the copiously flowing secretion. It is of 

 course presupposed that the parasites are not of any considerable 

 size ; for, in such a case, an alteration in the functional activity of 

 the surrounding organ could at most induce the inmate to make a 

 spontaneous emigration. 



As to worms occurring in the parenchyma, the healing art can 

 only avail when they occur in superficial organs, and then only opera- 

 tively. Thus, the well-known Filaria Medinensis may be gradually 

 wound out from the sub-epidermal tissue, and the bladder-worm may be 

 extracted from the eye (as has lately been done repeatedly, especially by 

 von Graffe) like cataract. We know, too, of numerous instances where 

 Echinococcus has been removed from the liver and other internal 

 organs by a fortunate operation, such as opening the cyst by means of 

 caustic paste, by the application of electricity after previous puncture, 

 by injection of tincture of iodine or other irritant reagents. On the 

 whole, however, we are comparatively powerless against such para- 

 sites. And the same may be said with regard to the brood of young 

 worms whose wanderings in the body, after boring through the wall 

 of the intestine, we have hardly any means of preventing. Against 

 these prophylaxis is our only security, and on this we may here lay 

 the greatest emphasis, and claim for it more attention than it has yet 

 received. 



But before we can comply with the conditions of the prophylactic 

 method, we must, above all things, know the ways and means by which 

 parasites and their germs are introduced. We must, in other words, 

 study the life-history of the several parasites, for this alone can put us 

 in possession of the desired information. In this connection hel- 

 minthology has still a mighty task before it, for as yet there are but 

 few human Entozoa whose history and fate are perfectly determined. 

 We do not wish to conceal the difficulty of the problem ; it will yet 

 be long before we can boast of a perfect solution. But the end is- 



