MEDICAL PROBLEM. 53 



within one human, it becomes necessary for them to have 

 an intermediary host or *' nnrse," as it has been termed. 

 In this capacity Culex is said to act; the theory further 

 calls for the death of Culex and the taking into the hu- 

 man system the further matured Filaria through "water 

 in which Culex has died. IManson's experiments are in- 

 teresting. They are commented on by Dr. Cobbold, who 

 was strongly impressed. Sonsino ^°'^ has also written on 

 this theory. 



King ^^ has, in a very readable way, brought charges 

 against Culex as the cause of malarious diseases. He 

 reasons on the fact that mosquitoes are found where ma- 

 laria abounds. It seems to us, as it does to Stebbins,^'^^ 

 that the reasoning should have proceeded in the reverse 

 direction. Malaria and Culex are widely separated at the 

 seashore, as many can testify who leave their city homes 

 to escape the former and are persecuted by the latter. 



Liegard narrates the symptoms produced by Culex 

 pungicus in France, and an account of the serious effects 

 of an unknown species in the city of Mexico is given in 

 "Science." 182 * 



Vague and unsatisfactory as these charges seem to be, 

 they are sufficiently suggestive as to warrant greater atten- 

 tion than they have yet received. 



Against Musca we find much graver charges and more 

 direct evidence. 



The published researches of Grassi ^^ have been of re- 

 cent years the most important, and those on which other 

 papers have been based. Packard ^^^ abstracts the above, 

 and states that they " go to show that flies are agents in 

 the diffusion of infectious maladies, epidemics, and even 

 infectious diseases." 



