HISTORY 7 



1854, and finally Pasteur in 1860 removed one by one the last 

 straws to which the sinking theory of spontaneous generation 

 was still clinging. 



With the exception of tapeworms and some intestinal round- 

 worms, one of the first worm parasites to be discovered in man 

 was Trichinella, in its larval stage in the muscles, this discovery 

 being made by Peacock in 1828. The hookworm was discovered 

 by Dubini in Italy in 1838; the blood fluke and the dwarf tape- 

 worm by Bilharz in Egypt in 1851; Filaria (larvae) by Demar- 

 quay in 1863; the Chinese human liver fluke by MacConnell 

 in India and MacGregor in Mauritius in 1874; the adult Filaria 

 by Bancroft in 1876. The first parasitic protozoan to be dis- 

 covered and recognized as such was the ciliate, Balantidium 

 coll, a cause of dysentery, discovered by Malinsten in 1856. 

 The spirochaete of relapsing fever was discovered by Obermeier 

 in 1873; the dysentery ameba by Losch in 1875; the malaria 

 parasite by Laveran in 1880; the sleeping sickness trypanosome 

 by Forde and Button in 1901 ; the Leishman bodies of kala-azar 

 by Leishman, and independently by Donovan, in 1903; the 

 spirochaete of syphilis by Schaudinn in 1905. 



Knowledge of the complicated Ufe histories characteristic of 

 many parasites practically began with Zenker's demonstration 

 of the life cycle of Trichinella in 1860 and Leuckart's experimental 

 proof of the strange life cycle of the beef tapeworm in 1861. 

 In 1874 Weinland discovered the snail in which the liver fluke 

 develops, though the relation of flukes to molluscs had been 

 previously suspected. In 1879 the epoch-making discovery of 

 the role of the mosquito in the development of filarial worms was 

 made by Manson and the science of Medical Entomology was 

 born. This discovery has been so far reaching in its results and 

 it has revolutionized preventive medicine to such an extent that 

 it may justly be looked upon as marking the beginning of a new 

 era in the history of preventive medicine, comparable with the 

 discovery of the germ causation of disease. One of the first 

 and certainly the greatest outcome of the discovery was the 

 discovery by Ross in 1898 of the relation between mosquitoes and 

 malaria. Other important discoveries concerning life histories 

 and modes of infection quickly followed. The transmission of 

 trypanosome diseases by tsetse flies was discovered by Bruce in 

 1893; the relation of mosquitoes to yellow fever by the American 



