172 PARASITIC ENTOZUA FROM A TOOTH. 



tlie Postal Microscopical Society. With a little difficulty I finally 

 succeeded in remounting the young cercaria in balsam, thus 

 rendering the body nearly transparent for microscopical examina- 

 tion. It measures nearly a sixth of an inch in length. Its head, 

 which is of a pale yellowish brown colour, is terminated by a 

 buccal opening of a contractile, sucker-like nature. The hyaline 

 integument of the body throughout is broken up by a series of 

 longitudinal and transverse markings, which presents an appear- 

 ance of irregularly shaped, tesselated cells. The ventral opening 

 is situated at the lower third, where a considerable cleft 

 occurs, and here is seen to be the termination of a narrow gut, 

 which runs from just below the buccal opening to this point, 

 and is then lost to view. The lower third of the body constitutes 

 what is nominally described as a tail-like appendage in the larval 

 stage, and which is either broken off or absorbed in the fully- 

 matured fluke. 



Filaria have now been found in almost every cavity of the 

 body, either in man, or in the lower animals, and it is not difficult 

 to conceive how several of these minute embryos may have 

 become lodged in the cavity of a hollow tooth of one among a 

 class of persons who notoriously disregard the use of the tooth- 

 brush. 



The insect world is vast almost beyond our concejition. The 

 President of the London Entomological Society states that while 

 Linnaeus knew only 3,000 species of insects 120 years ago, the 

 collections of the world probably include at present 200,000 or 

 250,000 species. Certain data lead to the inference that we do 

 not yet possess more than one-tenth of those existing, so that even 

 the jjrescnt rapid rate of discovery will not complete our collec- 

 tions of insects in less than 1,000 years. Before the end of that 

 period, many species of to-day will have become extinct, and the 

 President urges that those likely soon to disappear shoukl be 

 especially sought. 



