INTRODUCTION 13 



coccidian, Klossia helicina, in the excretory organ of Helix and 

 Eimer (]870) made an extensive study of Coccidia occurring 

 in various animals. Balantidium coli was discovered by Malm- 

 sten in 1857. Lewis in 1870 observed Entamoeba coli in India, and 

 Losch in 1875 found Entamoeba histolytica in Russia. At the be- 

 ginning of the last century, an epidemic disease, pebrine, of the 

 silkworm appeared in Italy and France, and a number of biolo- 

 gists became engaged in its investigation. Foremost of all, Pas- 

 teur (1870) made an extensive report on the nature of the causa- 

 tive organism, now known as Nosema bombycis, and also on the 

 method of control and prevention. Perhaps this is the first scien- 

 tific study of a parasitic protozoan to result in an effective prac- 

 tical method of control of its infection. 



Lewis observed in 1878 an organism which is since known as 

 Trypanosoma lewisi in the blood of rats. In 1879 Leuckart created 

 the group ''Sporozoa," including in it the gregarines and coccidi- 

 ans. The groups under Sporozoa were soon definitely designated. 

 They are Myxosporidia (Biitschli, 1881), Microsporidia (Balbi- 

 ani, 1882) and Sarcosporidia (Balbiani, 1882). 



Parasitic protozoology received a far-reaching stimulus when 

 Laveran (1880) discovered the malarial parasite in the human 

 blood. Smith and Kilborne (1893) demonstrated that the Babe- 

 sia of the Texas fever of cattle in the southern United States was 

 transmitted by cattle ticks from host to host, and thus brought 

 to light for the first time the close relationship which exists be- 

 tween an arthropod and a parasitic protozoan. Two years later, 

 Bruce discovered Trypanosoma brucei in the blood of horses and 

 cattle suffering from "nagana" disease in Africa, and in the fol- 

 lowing year he showed by experiments that the tsetse fly trans- 

 mits the trypanosome from host to host. Studies of malarial dis- 

 eases continued and several important contributions appeared. 

 Golgi (1886, 1889) studied the schizogony and its relation to the 

 occurrence of fever and was able to distinguish two types of fever. 

 MacCallum (1897-1898) found in the United States the union of 

 a microgamete and a macrogamete of Haemoproteus of birds. 

 Almost at the same time, Schaudinn and Siedlecki (1897) showed 

 that anisogamy results in the production of zygotes in Coccidia. 

 The latter author published later correct observations on the 

 Ufe-cycle of Coccidia (1898, 1899). 



Ross (1898) showed how Plasmodium praecox was carried by 



