1900.] Malaria and Mosquitoes. 295 



WEEKLY EVENING MEETING, 



Friday, March 2, 1900. 



His Grace The Duke of Northumberland, E.G. F.S.A., 

 President, iu the Chair. 



Major Konald Eoss, D.P.H. M.E.C.S. 



Malaria and Mosquitoes. 



Our knowledge of the disease called malarial fever first emerges 

 from chaos in the seventeenth century, when, owing to the recent 

 discovery of quinine, the great Italian physician, Torti, was ahle 

 to differentiate this malady from other fevers, and to describe its 

 symptoms with accuracy. Next century, Morton, Lancisi, Pringle 

 and others observed the connection of the disease with stagnant water 

 and low-lying ground, and first emitted the theory — which in one 

 form or another has found general acceptance up to the present date 

 — that the fever is due to a miasm which rises from the soil or water 

 of malarious localities. The next great advance was made in the 

 middle of the nineteenth century by Meckel, Virchow and Frerichs, 

 who ascertained that the distinguishing pathological product of the 

 disease is a black substance, which is distributed in collections of 

 minute coal-black or brown granules in the blood and organs of 

 patients, and which is called the malarial pigment or melanin. This 

 line of research culminated in the great discovery of Laveran in 1880 

 — to the effect that the melanin is produced within the bodies of vast 

 numbers of minute parasites which live in the red blood-corpuscles 

 of the patient. 



Pay Lankester had already opened the science of the parasitology 

 of the blood-corpuscle by his discovery of Drejoanidium ranarum in 

 frogs ; and it was at once apparent that the parasites found by these two 

 observers are somewhat nearly allied — that is, that Laveran's parasite 

 is a Protozoal organism, and not a vegetable one like the pathogenetic 

 organisms recently discovered by Pasteur, Lister, Koch and many 

 others. And our knowledge of the subject was quickly increased by 

 the discovery of similar hasmatozoa in certain species of reptiles, birds, 

 monkeys and bats, and in cattle, by Danilewsky, Kruse, Labbe, Koch, 

 Dionisi, Smith and Kilborne. In 1885 a further advance was made 

 by Golgi, who ascertained that the human parasites propagate within 

 the body of the host by means of ordinary asexual spore-formation ; 

 that the exacerbations of fever in a patient are coincident with the 

 disruption of the clusters of spores produced by the organisms : and 

 that there are at least three varieties of the parasites in man in Italy. 



