THREADWORMS. 83 



If this view does not convey the whole truth, it 

 is at all events correct as far as it goes, and 

 constitutes an important advance in our knowledge 

 of the development of this worm. Moreover it has 

 received in the main substantial confirmation from 

 the still more recent and elaborate researches of 

 Professors Zenker and Heller. To the last named 

 observer, whose acquaintance some of you made 

 when he was over in this country last summer, I am 

 indebted for the hint already named, as to the best 

 modes of artificially rearing oxyurides, and I have 

 also to acknowledge other useful contributions at 

 his hands. From the united labours of these two 

 savans it is now quite certain that the entire deve- 

 lopmental phases of oxyuris are accomplished within 

 the intestinal canal of the human bearer; and for 

 this end it is not necessary that the eggs should 

 find a new, or rather a second human bearer. In 

 other words, the person already suffering from 

 Oxyurides may increase the numbers of his enemies 

 to any extent by accidentally conveying the eggs or 

 worms lodged in the region of his anus into his 

 mouth. This he may do during sleep quite un- 

 consciously ; so that it is not fair to charge persons 

 who are the victims of this disorder with uncleanli- 

 ness. On the other hand, it occasionally happens 

 that due care in this respect has not been exercised, 

 and from such persons you may remove the eggs of 

 oxyurides from the margins of the finger nails. 

 G 2 



