242 INFECTION AND IMMUNITY 



days in another type. When a daily paroxysm oc- 

 curs, this is believed to be due to the alternate de- 

 velopment of two groups of parasites of the tertian 

 variety, as it has not been possible to distinguish 

 the parasite found in the blood of persons suffering 

 from a quotidian form of intermittent fever from 

 that of the tertian form. Very often, also, the daily 

 paroxysm occurs on succeeding days at a different 

 hour, while the paroxysm every alternate day is at 

 the same hour, a fact which sustains the view that 

 we have to deal, in such cases, with two broods of 

 the tertian parasite which mature on alternate days. 

 In other cases there may be two distinct paroxysms 

 on the same day and none on the following day, 

 indicating the presence of two broods of tertian 

 parasites maturing at different hours every second day. 

 The hypothesis that malarial infection results from 

 the bites of mosquitoes was advanced and ably sup- 

 ported by Dr. A. F. A. King, of Washington, D. C, 

 in a paper read before the Philosophical Society on 

 February 10, 1883, and published in the Popular Sci- 

 ence Monthly in September of the same year. In 

 1894 Manson supported the same hypothesis in a 

 paper published in the British Medical Journal (De- 

 cember 8th), and the following year (1895) Ross made 

 the important discovery that when blood containing 

 the crescentic bodies was ingested by the mosquito 



