120 MALARIA [CH. 



to Europe in the seventeenth century of Cinchona and its 

 alkaloids, it being then possible to distinguish types of fever 

 curable by quinine from those not affected by this drug. 



A third feature of malaria, namely its frequent association 

 with paludic conditions, although it seems to some extent 

 to have been known to the ancients {e.g. Varro, ii6 B.C.), was 

 first fully realized as a result of the work of Doni, Morton, 

 Lancisi and others, from the seventeenth century onwards. 

 This association was explained as shewing that malaria was due 

 to exhalations from decaying vegetable matter, or to minute 

 forms of life present in such exhalations. Hence there resulted 

 the Miasm theory of malaria, a theory universally held by 

 mankind up to a few years ago and responsible for the name 

 " Malaria " (=bad air). 



In 1847 the occurrence of the characteristic pigment of 

 malaria in the blood and organs was discovered by Meckel ; 

 this pigment, it was thought, was the result of the chemical 

 action of miasm on the blood. 



In 1881 Laveran discovered the organism containing this 

 pigment now known as the malarial parasite. Within a few 

 years Laveran's organism, the first discovered protozoon 

 parasitic in man, was universally recognized as the cause of 

 malaria. Thus in modern usage it has followed that no diag- 

 nosis which has not been based upon the demonstration of this 

 parasite, or its characteristic pigment in the blood, is accepted 

 as of any value in a crucial case, malaria now being an example 

 of a disease defined not on clinical but on parasitological 

 grounds. 



In 1886 Golgi demonstrated the nature of the life-cycle of 

 the parasite in man, and shewed that the periodicity of the 

 febrile attacks was dependent on the length of the cycle of 

 development of successive broods of the parasite, and that the 

 attack of fever occurred at the time when such broods simul- 

 taneously broke up into the spores which restarted the cycle. 

 Golgi also differentiated two species of malarial parasite, the 

 parasites of quartan and of tertian malaria, respectively. 



In 1891 Marchiafava and Bignami, after studying certain 

 irregular fevers prevalent in Rome in the summer and autumn, 



