390 ANIMAL BIOLOGY 



Proceeding on the theory that since fermentation is the result 

 of the activities of microorganisms, certain diseases of plants and 

 animals are likewise caused by the invasion of the body by similar 

 germs, Pasteur's early success in preventive medicine came from 

 the study of cholera in French Fowls and anthrax in Sheep and 

 Cattle. The treatment he employed reduced the death rate of the 

 animals from about ten per cent to less than one per cent, and saved 

 the French nation in twenty years not less than the amount of the 

 war indemnity of 1871. Then Pasteur devised the treatment for 





A B 



Fig. 245. — Endamoeba histolytica, a parasitic Amoeba of the human in- 

 testine, which gives rise to amoebic dysentery. A, active Amoeba showing 

 nucleus and three ingested human red blood corpuscles; B, encysted Amoeba 

 with four nuclei, preparatory to division into four individuals. (Redrawn, 

 after Dobell.) 



rabies. The human fatalities from this disease, usually arising by 

 infection from the bite of a 'mad' Dog, fell almost at once from 

 nearly one hundred per cent to less than one per cent. 



During the past half-century a host of investigators, following 

 the lead of Pasteur, have secured undreamed-of results in discover- 

 ing preventive measures and curative treatments for a long series 

 of diseases of Man, domestic animals, and plants. One thinks im- 

 mediately of diphtheria, tuberculosis, bubonic plague, typhus 

 fever, malaria, yellow fever, syphilis, amoebic dysentery, and 

 African sleeping sickness — all the results of the infection of Man 



