353 



located. Once boxed up inside the hold of a vessel, the contaminated mos- 

 quito may be reduced to the necessity of drawing its blood-supply (faute 

 de mieux) from lower animals, such as rats, etc. and to lay its eggs in any 

 collection of fresh water that may have found its way through the chinks 

 or otherwise. On land, mosquitoes will instinctively frequent the basement 

 or ground floor of houses in preference to the upper ones, and they seldom 

 seek the open air of their own accord, while their usual functions can be 

 fulfilled under shelter, except when they are ready to lay their eggs. This 

 is in accordance with the maternal instinct which teaches them to procure 

 undisturbed possession of some stagnant waters for their larvae during 

 the two or more weeks required for the complete development of the wing- 

 ed insect ; a condition seldom satisfied within inhabited dwellings. On the 

 approach of its natural death, the parent insect returns to the same water 

 where the eggs have been laid, and its cadaver remains floating on the 

 water, to be devoured up its own larave. Entrapped during the unconscious 

 act of a person putting on his hat in a contaminated locality, mosquitoes" 

 have been conveyed to distant houses ; and inside of boxes, trunks, parcels 

 etc. provided that a sufficient degree of moisture and particles of available 

 food exist in their place of confinement, they can be conveyed to any dis- 

 tance that may be reached within the natural term of the insect's life 

 (which sometimes lasts as many as thirty or thirty-five days.) 



My experiments upon yellow-fever mosquitoes have already been 

 published; their results may be thus briefly recorded; first reproduction 

 of the disease, in a mild form, within five to twenty five days after having 

 applied contaminated mosquitoes to susceptible subjects; second, partial 

 or complete immunity against yellow-fever, obtained even when no pathol- 

 ogic manifestation had followed those inoculations; third, finally, the 

 coincidence of cultures made with the heads and proboscis of contaminat- 

 ed mosquitoes giving the identical mierococus in tetrads (M. tetragenus 

 febris flavae; M. tetragenus versatilis, Sternberg; tetracoccus versatilis) 

 previously discovered by me, in colaboration with Dr. C. Delgado, in the 

 blood and secretions of yellow-fever patients. 



With such an array of evidence (presumptive or otherwise) as to the 

 role of the mosquito in the propagation of yellow fever, and the concur- 

 rence of Koch, Manson, and other experts of the highest order in their 

 advocacy of a similar doctrine for the transmission of malaria, the time 

 seems at last come when decided measures of protection against mosquitoes 

 should be seriously considered ; the more so as the energetic spirit of the 

 Anglo-Saxon race is about to replace the fatalistic apathy of former rulers 

 in Cuba and Porto Rico. 



The suggestion of Koch, calling for dwellings from which mosquitoes 

 could be barred out, in order that the German colonies of eastern Africa 

 might be freed from malaria, ought surely to be acted upon in countries 

 where it is not only malaria that has to be contended with, but also the 



