1^16] Swezij: Kinetonuclevs of Flngellates 207 



especially among the haemoflagellates, has become a matter of some 

 confusion, and a word concerning the application of these terras in 

 the present discussion will not be out of place. The basal granule com- 

 plex has two distinct functions in many if not most of the flagellates, 

 that is, as the definitive basal granule for the flagellum, and also as the 

 division center for the cell. The latter function may be displayed 

 either as the actual centrosome on the spindle, or as the organelle 

 whose division begins the process in the entire cell. It may occasion- 

 ally happen, as in one or two figures in the division cycle of Tricho- 

 monas augusta (Kofoid and Swezy, 19156), that the blepharoplast be- 

 comes separated into two granules, one of which functions as the cen- 

 trosome and the other as the basal granule. This is an exceptional 

 occurrence, however, and in all cases in which it does not occur the 

 term blepharoplast is applied to the granule complex. A further dis- 

 cussion of the term blepharoplast as applied to the parabasal body is 

 given below. With the casting aside of the word kinetonucleus, the 

 term trophonucleus becomes superfluous in the terminology of the try- 

 panosomes, that structure then becoming the nucleus as in all other 

 flagellates. The centrosome is the granule which by its own division 

 initiates division in the cell, and, in the metazoan cell is surrounded by 

 achromatic material which becomes the eentrodesmose and central 

 spindle. This latter structure has no relation whatever to the darkly 

 staining fibril frequently found connecting the blepharoplasts in 

 division in many of the flagellates. To this fibril the term paradesmose 

 has been applied (Kofoid and Swezy, 1915a. b) as more correctly 

 interpreting its function and origin. Centrodesmose is limited to the 

 achromatic material of the central spindle. 



The efl:'ects of parasitism on the protozoan cell are as yet but little 

 understood, but it is certain that profound changes result from the 

 attempts of the organism to adapt itself to its new environment in the 

 various stages of its life as a parasite. In changing from a fluid to a 

 semi-fluid medium, or to one filled with food or with blood cells, the 

 greatest stress falls naturally upon the motor apparatus. This has 

 been met in two ways, first, by the formation of an undulating mem- 

 brane and second, by the growth of additional structures related to the 

 basal granule of the flagella but intracytojilasmic. That these are 

 adaptations conditioned on a parasitic mode of life is shown by the 

 general lack of them in the free-living flagellates and the almost uni- 

 versal occurrence of one or the other, or of both, among parasitic 

 species. 



