iStlS] SuTSij: Kinetonudeiif: of Flagdhitcs 229 



apparatus. Its homology with the "kinetoniicleiis" of the trypano- 

 somes he rejects on the ground that the latter is a second nucleus. 

 His conclusions in regard to the function of the parabasal body of 

 Trypanoplasma agrees with the ideas that have been brought out here. 

 His error lies in ascribing to that structure in the trypanosomes a 

 value which it does not possess, and in failing to note its homology 

 with the parabasal body of Trypanoplasma. 



That this organelle is not the main center of kinetic activity of the 

 cell is shown in the "blepharoplastlose" trypanosomes of Werbitzki 

 (1910), where its loss was followed bj' no diminution of kinetic 

 activity. Its intimate connection with the motor apparatus suggests 

 that its function is that of an accessory kinetic structure, or kinetic 

 reservoir, secondary to the blepharoplast, which is the chief kinetic 

 center or nucleus, and is related to the metabolic processes incident 

 to increased motor activity resulting from a parasitic mode of life, 

 and may possibly be, as Alexeieff (1910) has suggested, a mass of 

 reserve material. On this account the term coined by Janicki (1911), 

 "parabasal body," is a more appropriate name for this structure than 

 any of the others which have been commonly applied to it, and its 

 general adoption for these structi;res is hereby proposed. 



All of the facts thus far brought out point to the same conclusion 

 in regard to this structure in Prowazekia, Polymastix, Trichomonas, 

 and the Trichonymphida, that is, that it is an accessory part of the 

 motor apparatus, correlated with an endoparasitic mode of life. 



It has already been pointed out in the discussion of the various 

 flagellates which possess " kinetonuclei " that the division of these 

 structures is in no sense mitotic. The idea, however, has been ad- 

 vanced by those (Sehaudinn, 1904, Minchin, 1912) who do not hold 

 the centrosomic view of its function above sketched, but who do re- 

 gard it as a secondary nucleus, that it contains a centrosome by which 

 its own division is controlled. Minchin (1912) terms this centrosome 

 the "centrosome blepharoplast" and claims it as the basal granule of 

 the flagellum. Proof on this point, however, is entirely based on 

 pathogenic or abnormal figures and erroneous interpretation. The 

 true blepharoplast, as we have used the term, initiates division in the 

 cell by dividing first (Wenyon, 1913, Minchin and Thomson, 1915) 

 but 110 evidence lias yet been produced by any investigator to sliow 

 that it actually functions as a centrosome on a spindle for the division 

 of the "kineto nucleus" by mitosis. 



