REMEDIES AGAINST MOSQUITOES 193 



lish language as spoken by Englishmen, who invariably 

 term it paraffine or j)araffine oil. To the Italians we are 

 indebted for a useful expression, which we might just as 

 well adopt, namely to '' peirolke^' meaning to treat waters 

 with kerosene. Example : The petrolizatioii of mosquito- 

 breeding i^ools is one of the most important measures to 

 be undertaken in the warfare against mosquitoes. 



Many of the small-scale experiments which have been 

 made, notably by the Italians, with a small number of 

 mosquito larvtB in small jars or puddles, are not so in- 

 dicative of the results to be ex^^ected as are more natural 

 and large-scale conditions. Mr. Matheson tells me that 

 he once took tw^euty-five larvne in a quart jar and cov- 

 ered it with a thin film of common kerosene oil and no- 

 ticed that in less than fifteen minutes all larvae were dead. 

 At the same time he put a film of oil on the surface of a 

 thirty-gallon tank, and at the end of an hour there w^ere 

 still some few larvae wriggling. He questions whether 

 kerosene is as swift a larvicide if put on the surface of 

 deep ponds, as it is on the surface of experimental jars. 

 In my owai w^ork I discovered that wdiere the oil was not 

 distributed equally the larvae clustered in the free places 

 and were able to support life for hours. 



Otlici' Snhdtuiccs Agahist fhe Earhj Stages of 

 Mosquitoes. 



The last paragraph indicates plainly the fact that 

 laboratory experiments with other substances must not 

 be accepted as conclusive until the substances used are 



