PSYCHE. 



383 



their gathei'ing in the holds of vessels, 

 in which the source of yellow-fever in- 

 fections has been, many a lime, dis- 

 tinctlv located. Once boxed up inside 

 the hold of a vessel, the contaminated 

 mosquito may be reduced to the neces- 

 sity of drawing its blood supply (/ante 

 dc micii\) fiom lower animals, such as 

 rats, etc., and to lay its eggs in anv 

 collection of fresh water that niav have 

 i'ound its. way through the chinks or 

 otherwise. On land, mosquitoes will 

 instinctively fre(|ueiit the basement or 

 ground Hoor of houses in preference to 

 the upper ones, aiul thev seldom seek 

 the open air of their own accord, while 

 their usual functions can be fulfilled 

 under shelter, except when thev are 

 reatlv to la\ their eggs. This is in 

 accordance with the maternal instinct 

 which teaches them to procure undis- 

 tuibed possession of some stagnant 

 waters lor their lar\"ae during the two 

 or more weeks recjuired for the com- 

 l^l'ete development of the winged insect; 

 a condition seldom satisfied within 

 inhaliited dwellings. On the approach 

 of its n.itural death, the parent insect 

 returns to the' same waters where its 

 eggs have been laid, and its cadaver 

 remains floating on the water, to be 

 devoured by its own laivae. Entiapped 

 during the unconscious act of a person 

 putting on his hat in a contaminated 

 locality, mosquitoes may be con\•e^•ed 

 to di^tant houses; and inside of boxes, 

 trunks, paicels, etc., provided that a 

 sufticient degree of moisture and par- 

 ticles of availal.le food exist in their 

 place of couHuemenl. they can lie 



conveyed to any distance that rnay 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 pub- 

 lished ; 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 pathogenous manifesta- 

 tion had followed those inoculations ; 

 thiid. finally, the coincidence of cultuies 

 made with the heads and proboscides 

 of contaminated mosquitoes giving the 

 identical micrococcus in tetrads (M. 

 tetragenus febris flavae ; M. tetragenus 

 versatilis, Sternberg; tetracoccus ver- 

 satilis) previously discovered by me, in 

 collaboration with Dr. C. Delgado, in 

 the blood ;md secretions of yellow-fever 

 patients. 



With such an array of evidence (pre- 

 sumptive or otherwise) as to the r61e of 

 the mosquito in the propagation of yel- 

 low fever, and the concurrence of Koch, 

 Manson, antl 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 ener- 

 getic spirit of the Anglo-Saxon race is 

 about to replace the fatalistic apathy of 

 former rulers in Cuba and Porto Rico. 

 I'he suggestion of Koch, calling for 



