80 LECTURES. 



The human threadworms, properly so called, refer 

 exclusively to the species termed Oxyuris vermicu- 

 laris, which may emphatically be called the children's 

 pest. Although its presence within the human 

 body is seldom attended with fatal results, there is 

 no entozoon more universally distributed amongst 

 the younger members of our race. At the same 

 time it is an entire mistake to suppose that it con- 

 fines its attacks to young persons, since we are liable 

 to play the part of host at any age. Some persons, 

 indeed, are all their lifetime subject to this dis- 

 agreeable form of helminthiasis. 



As I have stated in the second edition of my 

 smaller treatise (now out of print), the existence of 

 oxyuris, as happens also with some other entozoa, is 

 not limited to either hemisphere, though it appears 

 to be rather more abundant in warm than in cold 

 climates. In this country it is not so frequent as 

 on the Continent ; nevertheless, with such data as 

 have been placed before you thus far, I have been 

 led to hazard the statement, that probably about 

 one-tenth of our island population are actually 

 infested by this minute worm. Be the truth of that 

 conjecture proven or disproven, as the case may be, 

 by subsequent investigations, it is more consolatory 

 to be able to affirm that of those who are thus 

 called upon to play the part of host only a very small 

 proportion really suffer serious inconvenience. 



The general appearance of the Oxyuris vermi- 



