140 3I0SQUiT0ES 



of the city. Some part of it must also be attributed to 

 the excellent quarantine service under the charge of the 

 United States Marine Hospital Service, but also, without 

 doubt, much of the result must further be attributed to the 

 hospital and barrack methods, and treatment of mosquito 

 breeding-places carried on under the direction of the 

 medical corps of the army. 



Mosquitoes and Filariasis. 



The first evidence scientifically obtained that mosqui- 

 toes play a part in the spread of a disease was in the case 

 of the parasitic worms of the genus Filaria, which are re- 

 sponsible in Oriental tropical regions for the terrible 

 disease known as elephantiasis. The adult worm lives in 

 the skin of different parts of the body, lodged in the 

 lymphatic vessels. The two sexes are found side by side, 

 and are capable of living there a long time. They ob- 

 struct at certain points the flow of the lymph. This ac- 

 cumulates and dilates the vessels and the lymphatic 

 spaces. This mechanical distention is accompanied by 

 an irritation of the vessels and of the surrounding con- 

 nective tissue. Thus, elephantiasis becomes established, 

 which, as is generally known, manifests itself in very dif- 

 ferent degrees and occupies different parts of the body, 

 such as the arm, the leg, or the scrotum. 



The female Filaria enclosed in the lymphatic ^^essels 

 is viviparous. The embryos to which she gives birth 

 spread in the lymph and then with it into the blood, and 

 it is in the blood that they are comnionl3" observed. 



