ON MALARIA PARASITES OF THE ORANG-OUTAN. 



By G. Shibayama. 2 

 {From the Institute for Infectious Diseases, Tokio. 



The first and only investigation of the malarial parasite in the orang- 

 outan was made by Halberstaedter and Prowazek in Java in the year 

 1907, while reports on the malarial plasmodium of Maccacus are not lack- 

 ing in the literature. By a comparative study, the authors established 

 the species diagnosis between the parasite of Maccacus and that of the 

 orang-outan. 



The plasmodium of the orang-outan which I have studied and 

 which is illustrated in the accompanying plates does not differ from the 

 Plasmodium petheci spec. nov. Halb. u. Prow., except in the absence of 

 stippling ("Zipfelung") of the red blood corpuscles. The young forms 

 appear as small rings which, as in the case of the tropical parasite of man, 

 are composed of a nucleus staining red and of a crescent-like mass of 

 protoplasm staining blue. Eibbon-like forms resembling those of the 

 quartan parasite of man are also observed. In the adult parasite a 

 vacuole appears between the nucleus and the protoplasm, and rod-like 

 pigment granules are also present. The chromatin of the nucleus enlarges 

 and becomes differentiated as the parasite increases in size. 



The sexual forms resemble the quartan parasite in respect to- pigmenta- 

 tion and staining reactions. The male sexual forms are rich in chromatin. 

 * The protoplasm takes a paler stain and is but slightly pigmented. The 

 female gametocytes on the contrary contain dark protoplasm and are 

 rich in pigment. The schizogony of the parasite of the orang-outan 

 takes place after the manner of the human tertian parasite. The nucleus 

 of the schizonts divides into 12 to 16 parts, most of the pigment being 

 situated in the center of the cell. 



'Read at the first biennial meeting of the Far Eastern Association of Tropical 

 Medicine, held at Manila, March 12, 1910. Translated from the German. 

 - Delegate from His Imperial Japanese Majesty's Government. 



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