APPENDIX. 

 PATHOGENIC PROTOZOA. 



Protozoa are unicellular animal organisms. As they are 

 studied by methods that have much in common with those 

 used for the bacteria they may be considered here briefly. 

 Protozoa are numerous in pond and ditch water, and these 

 species seem to be harmless. However, many diseases of 

 the lower animals are caused by protozoa, such as surra, Texas 

 fever and coccidium disease of rabbits. Birds,* reptiles and 

 frogsf may show organisms in the blood resembling the para- 

 sites of malaria. Until recently it has been doubtful whether 

 any pathogenic protozoon has ever been propagated in pure 

 culture outside of the body of the host. This has been accom- 

 plished by Novy and MacNeal for a parasite (Trypanosoma) 

 from the blood of the rat J and from many species of birds § on 

 rabbit-blood-agar. 



Amceba dysenteriae (Amoeba coli). — ^Associated with 

 amebic dysentery and believed to be its causative agent is 

 the Amceba dysenieria, more often named Amceba coli. These 

 organisms are found in the intestinal ulcers, the feces, the 

 secondary liver abscesses and the sputum (in the latter only 

 when an amebic liver abscess has perforated into the lung). 

 The lesion in the colon is a severe inflammation accompanied 

 by necrosis chiefly of the submucous layer, and leading to ex- 



* Opie and MacCallum. Journal Experimental Medicine. Vol. III. 



t Langmann. New York Medical Journal. January 7, 1899. 



X Novy and MacNeal. Contributions to Medical Research. Dedicated to 

 Victor C. Vaughan. 1903. 



§ Novy and MacNeal. On the Trypanosomas of Birds. Journal of In- 

 jectious Diseases. Vol. II. No. 2. P. 257. March. 1905. 

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