3IALABIA AND MOSQUITOES 61 



There was no autoclitlionous case of malarial fever for 

 years at tlie League Island Navy Yard, although there 

 was a distinct breeding--o-round for xVnopheles near by. 

 Woldert has caug-ht larvjio of Anopheles in a clear pool of 

 water in the Pocono Mountains of Pennsylvania, a notable 

 health resort, at an elevation of three thousand feet above 

 sea-level. The statements that malaria has prevailed when 

 there were few or no mosquitoes are always too vague to 

 be of value, because it is not definitely stated whether the 

 cases w^ere relapses or fresh infections. In cases where 

 mosquitoes are numerous, moreover, and there is no mal- 

 aria, to the point which we have already made that prob- 

 ably no malaria has been brought into the vicinit}" may 

 be added the fact that when mosquitoes are numerous, 

 almost without exception they are found to be the com- 

 mon species of Culex, which, as shown, have nothing- to 

 do with malaria. It is often stated, for example, that 

 malarial fever is caused by excavating the ground ; newly 

 turned earth is said to be responsible for it, but, as a 

 matter of fact, as pointed out by Ross, there are millions 

 of people constantly engaged in digging without suffering 

 from the disease more than do others, and then also ex- 

 cavations always result in surface pools of water, m which 

 for a time Anopheles will frequently he found breeding. 

 One curi(ms case has been mentioned by Mr. D. E. Hutcli- 

 ings, in the English journal, Nature, in which he stated 

 that he knew of a medically authenticated case of malaria 

 having been caused by fresh earth carried past a Avindow 

 in buckets by coolies. This statement is criticized by 

 Ross in the following words : " Which fact was medically 



