122 LECTURES. 



the action of a single grain of this valuable drug. 

 The medical value of the anecdote is further in- 

 creased by the fact that the man had never com- 

 plained of parasitism of any kind, nor was he aware 

 of the medicinal character of the sweetmeat. No 

 doubt the lumbricus might sooner or later have 

 proved itself to be a troublesome guest, so that on 

 the whole the "host" must be congratulated on 

 this apparently providential interference in his 

 favour. 



As regards the rarer forms of human nematode 

 parasites, the only other species respecting which it 

 is necessary that I should say a few words is the 

 little Trichina spiralis. I have so fully enlarged 

 upon the history, structure, and development of 

 this entozoon elsewhere that I need only add a few 

 particulars. The disease produced by it was first 

 discovered, or rather diagnosed, by Professor Zenker, 

 of Erlangen ; but, for the antecedent discoveries re- 

 corded in this connexion, and also for a correct 

 knowledge of our later experimental researches, I 

 must refer you to the supplement of my larger 

 treatise on Entozoa. In my smaller book on 

 " Tapeworms and Threadworms " I have given a 

 concise statement of the practical bearings of the 

 subject; but as this volume is now out of print, 

 and as cases have recently occurred in the North 

 of England, I cannot be satisfied with merely re- 

 ferring you to what I have there said. The trichina, 



