340 THE FIGHT AGAITiST YELLOW FEVER. 



these he gave the name Stegomyia (fly which hides), and in this new 

 genus he established 22 species. It is one of these species, the Ste- 

 gomyia fasciata^ which to the exclusion of all others, transmits the 

 yellow fever parasite from the sick to the healthy man. This Ste- 

 gomyia, moreover, is the most cosmopolitan of all species of mosquitoes, 

 and its wide distribution explains the continuous spread of this terri- 

 ble malady since the discovery of America. 



Before entering into the blood of a man the fever germ must have 

 passed a period of incubation in the tissues of the mosquito, and vice 

 versa. This is a fact of prime importance. The sickne-^s of man 

 implies the sickness of the mosquito, and inversely. The mosquito's 

 illness, however, is light, scarcely perceptible, while that of man is 

 severe. If ever the human race arrives at the point of being freed 

 from the yellow-fever micro-organism, the Stegomyia fmciata will 

 be freed at the same time. Thus there is a sort of pathological com- 

 pact between man and the mosquito, a kind of unhealthy fellowship 

 of which the existence of this infectious bacillus is the binding force. 

 We may therefore believe that in order to eradicate this plague — that 

 is, the parasitic microbe — this fellowship must be dissol\^ed. The 

 healthy man must be isolated from the infected mosquito and the 

 healthy mosquito from the infected man. There would be no danger 

 in the contact of a healthy man with a healthy mosquito. That is the 

 theoretical idea. The practical sanitary scheme follows this formula : 

 To drive out the mosquito, to kill it, or to make it well. Only by 

 accomplishing separately one of these three aims, or all three at the 

 same time, have the sanitary authorities been successful in making- 

 healthy the island of Cuba, the Brazilian coast, and more recently the 

 territory of Dakar, in the French West African colony. Success has 

 been attained in purging these regions of the disease wdiich had 

 existed there in an endemic state, and in stifling at the start epidemics 

 threatened by imported infected cases. It is the same line of action 

 that will have to be follow^ed in every locality at each reappearance 

 of the disease until humanity is entirely freed from it. 



But to avoid the mosquito, or to find shelter from its bite, w^e must 

 know its mode of life, its customs, its habits, its peculiarities, or, in a 

 word, its com23lete life history. And that is just wdiat we have 

 learned from numerous researches by medical naturalists, among 

 wdiom must be named the members of three commissions organized by 

 the United States, English, and French Governments and sent to the 

 infected localities to stud}^ on the spot the evil and its remedies. 

 Mention must also be made of scholars from the Colonial Medi'^al 

 School of Liverpool and from the Institut Pasteur de Paris, who 

 have directed these studies and summarized the results. Besides 

 special memoirs, the perusal of wdiich is incomparable to gain a 

 knowledge of the subjects, several recent publications of a more gen- 



