INTRODUCTION 17 



this is the first scientific study of a parasitic protozoan to result 

 in an effective practical method of control of its infection. 



Lewis in 1878 saw an organism which is known since as Try- 

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

 the term "Sporozoa/' including in it the gregarines and coccidia. 

 Other groups of Sporozoa were soon definitely designated. 

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

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



Parasitic protozoology received a far-reaching stimulus 

 when Lavern (1880) discovered the malarial parasite in the 

 human blood. Smith and Kilborne (1893; demonstrated that 

 the Babesia 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 

 between an insect 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 

 following year he showed by experiments that the tsetse fiy 

 transmits the trypanosome from host to host. Studies of mal- 

 arial diseases continued and several important contributions 

 appeared. Golgi (1886, 1889) studied the schizogony and its re- 

 lation 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 Hae- 

 moproteus of birds. Almost at the same time, Schaudinn and 

 Siedlecki (1897) showed that anisogamy results in the produc- 

 tion of zygotes in Coccidia. The latter author then (1898, 1899) 

 published correct observations upon the life-cycle of Coccidia. 

 Ross (1898) showed how Plasmodium praecox was carried by 

 Culex fatigans and described its life-cycle. Since that time sev- 

 eral investigators have brought to light important observations 

 concerning the biology and development of these organisms and 

 their relation to man. In the present century, Forde and Button 

 (1901) observed that the sleeping sickness in Africa is also due 

 to an infection by Trypanosoma gamhiense. In 1903 Leishman 

 and Donovan recognized Leishmania of "kala-azar." 



Artificial cultivation of bacteria had contributed toward a 

 very rapid advancement in bacteriology, and it was natural, as 

 the number of known parasitic Protozoa rapidly increased, that 



