MALARIA. 369 



that the 'night air,' per se, is no more dangerous than the day air, but 

 that the real danger consists in the presence of infected mosquitoes of a 

 species which seeks its food at night. As pointed out by King, in his 

 paper already referred to, it has repeatedly been claimed by travelers in 

 malarious regions that sleeping under a mosquito bar is an effectual 

 method of prophylaxis against intermittent fevers. 



That malarial fevers may be transmitted by mosquitoes of the genus 

 Anopheles was first demonstrated by the Italian physician Bignami, 

 whose experiments were made in the Santo Spirito Hospital in Home. 

 The subjects of the experiment, with their full consent, were placed in 

 a suitable room and exposed to the bites of mosquitoes brought from 

 Maccarese, 'a, marshy place with an evil but deserved reputation for the 

 intensity of its fevers.' It has been objected to these experiments that 

 they were made in Eome, at a season of the year when malarial fevers 

 prevail to a greater or less extent in that city, but Marchiaf ava and Big- 

 nami say: 



"It is well known to all physicians here that, although there are some 

 centers of malaria in certain portions of the suburbs, the city proper is 

 entirely free from malaria, as long experience has demonstrated, and at 

 no season of the year does one acquire the disease in Eome." 



In view of the objection made, a crucial experiment has recently been 

 made in the city of London. The result is reported by Manson, as fol- 

 lows: 



"Mosquitoes infected with the parasite of benign tertian malarial 

 fever were sent from Eome to England, and were allowed to feed upon 

 the blood of a perfectly healthy individual (Dr. Manson's son, who had 

 never had malarial disease). Forty mosquitoes, in all, were allowed to 

 bite him between August 29 and September 12. On September 

 14 he had a rise of temperature, with headache and slight chilliness, 

 but no organisms were found in his blood. A febrile paroxysm occurred 

 daily thereafter, but the parasites did not appear in the blood until Sep- 

 tember 17, when large numbers of typical tertian parasites were found. 

 They soon disappeared under the influence of quinine."* 



We have still to consider the question of the transmission of malarial 

 fevers by the ingestion of water from malarious localities. Numerous 

 medical authors have recorded facts which they deemed convincing as 

 showing that malarial fevers may be contracted in this way. I have 

 long been of the opinion that while the observed facts may, for the most 

 part, be authentic, the inference is based upon a mistake in diagnosis. 

 That, in truth, the fevers which can justly be ascribed to the ingestion 

 of a contaminated water supply are not true malarial fevers — i. e., they 

 are not due to the presence of the malarial parasite in the blood. This 

 view was sustained by me in my work on 'Malaria and Malarial Diseases,' 



* Quoted from an editorial in the 'New York Medical Journal' of October 20, 1900.] 



