PRESIDENTIAL ADDRESS SECTION D. 83 



sections, devoted to studies with purely economic aims. The study 

 of comparative morphology, including embryology and some his- 

 tology, is indispensable. A knowledge of some animal life-histories 

 is also required. Early specialisation is to be deplored. The 

 specialist needs a breadth of outlook, an orientation in the whole 

 field of his science, in order to have balance and perspective, which 

 are absolutely necessary. 



Animal Parasitology. 



In this subject, which is a vast one, we may first note the use 

 made of protozoologists, helminthologists, and entomologists in the 

 Great War, more especially in America, where they were given 

 military rank. Thousands of examinations of blood smears for 

 malarial parasites, of stools for parasitic Protozoa and helminthic 

 ova, and experiments for the control of lice and of flies — to name 

 but two insects — were made. Several strains or pure lines of 

 Entamoeba histolytica, sometimes called Endamoeba dysenteriae in 

 America, the causal agent of amoebic dysentery, were definitelv 

 indicated as a result. In malaria the continued use of quinine for 

 three months after apparent recovery from malaria was indicated. 

 In helminthology, after the work of Japanese scientists regarding 

 the stages of Schistosoma (Bilharzia) japonic)/ m in snails, Leiper 

 determined the Gastropod hosts of S. haematobium and »S'. mansoni 

 in Egypt, and Porter, Cawston, and Becker have worked at the 

 problem in South Africa. Porter has now determined the life-cycle 

 and molluscan hosts of »S'. haematobium and jS'. mansoni, and 

 incidentally those of the African cattle fluke, Fasciola gigantica. 

 as well as those of F . hepatica in South Africa. 



The actual nature of the organism causing typhus, which is 

 transmitted by lice, still baffles us. But, being certain that it is 

 lice-borne, we now know an effective way of attacking typhus by 

 de-lousing campaigns, just as earlier, thanks to the labours of Sir 

 Ronald Ross, we know that anti-mosquito measures against 

 Anophelines will control malaria. Also, thanks to American inves- 

 tigators, we know that anti-mosquito measures against Stegomyia 

 fasciata will control yellow fever. The causal organism of yellow 

 fever is stated by Noguchi to be a spirochaete, Leptospira, icteroides. 



In Africa there is still a most important economic entomo- 

 logical problem to be investigated further, namely, the bionomics 

 of Glossinae or tsetse flies and their relation to big game, in order 

 to control various forms of trypanosomiasis, such as sleeping sick- 

 ness in man and nagana in cattle. In 1910 a second human 

 trypanosome, T. rhodesiense, was discovered. 



In protozoology important researches, affording interesting 

 evidence in the evolution of disease, have been carried on bv 

 Laveran and Franchini and by Fantham and Porter, who experi- 

 mentally introduced species of Herpetomonas into various verte- 

 brates. Leishmania in culture shows that it is a Herpetomonas, 

 and the experiments mentioned, on Induced herpetomoniasis, show 

 that Leishmania is an insect-borne Herpetomonas which can live 



