UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 16, No. 6, pp. 71-88, plates 9-1 1 December 11, 1915 



BINARY AND MULTIPLE FISSION IN 

 HEXAMITUS 



OLIVE SWEZY 



Historical. — The generic name Ocfoiitilus wa.s proposed by Pro- 

 wazek (1904) for a flagellate with eight flagella so minute that, until 

 within quite recent years, its form and number of flagella have been 

 matters of great uncertainty. A review of the earlier literature on 

 this genus has been given by Dobell (1909) and is not repeated here, 

 beyond a few facts necessary to justify the name I have given to it. 



The generic name, Hexamita, was proposed by Dujardin (1841) 

 and was later slightly modified by Biitsehli (1878) to Hexamitiis. 

 These organisms, though figured by both Dujardin and Biitsehli as 

 possessing six flagella, have since been conceded by most investigators 

 to be identical with the eight-flagellated form as it is now described. 

 The type form is H. inflatus Dujardin. a free-living flagellate. 



As Dobell (1909) has so well pointed out, the various names which 

 have been applied to this flagellate are not available, and there remains 

 only the original name, HcxaniHits, and the one proposed by Prowazek, 

 Octornifus, to consider. 



Prowazek (1904) created the genus Octomitus for a flagellate from 

 the rat, but his organism was very evidently only a form of what had 

 already been described as Hexamitus muris Grassi. 



Dobell (1909), recognizing Hexamitus inffains Duj. as the type 

 species of Hexamitus, claims that the parasitic forms must have a 

 diiferent generic name, and therefore proposes to recognize Prowazek 's 

 name Octomitus, thus making habitat and not morphological charac- 

 ters the basis of generic distinction. The accident or preference of 

 habitat is hardly one which can safely be used with these organi-sms 



