\ 



MEDICAL PROBLEM. 51 



Hersey^* considers them favorite food with the fly 

 catchers ; M'Lachlan ^* believes these attacks only inci- 

 dental ; and Thomas discusses the swallow iu this ca- 

 pacity. 



IV. 

 THE MEDICAL PROBLEM. 



The disao-reeraent between the two schools of students 

 relative to the annihilation of Culex and Musca seems to 

 be an almost irreconcilable one with the present light 

 which M^e now possess. 



A large and eminent school of scientists believe it un- 

 safe to overthrow the equipoise of Nature, or, more prop- 

 erly speaking, that due proportion of individuals in the 

 animal kingdom. They urge that Nature has eliminated 

 all useless species and that there is no safety in destroying 

 any living thing, lest we annihilate some function Avhich 

 will leave us far worse off for the need of it. 



But an equally numerous school take the ground that it 

 is incumbent upon man to first ascertain the exact nature 

 of any creature, and utilize or destroy as in his judgment 

 may seem best. With such creations as the Canada this- 

 tle, the potato beetle, or the Colorado grasshopper they 

 hold no parley. Without stopping to question its place in 

 the economy of Nature, they simply treat such pest as un- 

 alloyed evil, to be exterminated as quickly as possible, 

 gladly risking the effects of the outrage thus offered, that 

 the great evils worked by the species may be prevented. 



Whether the mosquito or house fly is to be treated 

 as an evil it is hardly possible to decide. If the more 

 harmful relatives of the house fly could be separated from 



