344 WOOLFORD B. BAKER. 



The so-called "kineto-nucleus" of trypanosomes appears in 

 approximately the same relation to the rest of the cell as does the 

 deeply staining chromatoid mass of the kinetic complex in Euglena 

 agilis. When one remembers the importance given to the 

 "kineto-nucleus" and the emphasis placed upon homologous 

 structures in other forms, in the development of the group 

 Binucleata, the interest attached to the comparable body in 

 Euglena agilis is increased. It is generally agreed by Proto- 

 zoologists the "kineto-nucleus" is neither a nucleus nor an active 

 kinetic center and the name should therefore be replaced by one 

 of greater significance. Among the terms suggested is " parabasal 

 body," first used by Janicki but redefined and used more ex- 

 tensively by Kofoid. 



Examination of the descriptions given of parabasal bodies and 

 their behavior by Janicki and others, shows striking similarity to 

 that of the chromatoid mass of the kinetic complex in E. agilis. 

 The parabasal body is closely connected with the kinetic elements 

 of the cell, and according to Kofoid serves as a reservoir of 

 substances which are used by the organism in its kinetic activities. 

 During mitosis the body behaves variously in different species. 

 In Devescovina striata, for example, it divides and the two daughter 

 parabasals are shown in constant relationship to the poles of the 

 extra-nuclear, rod-like, division spindle, where centrioles can 

 often be determined. In other cases, e.g., Lophomonas blattarum, 

 the parabasal body degenerates with approaching mitosis and a 

 new one is formed for each of the daughter animals produced. 

 In Euglena agilis, the granule which migrates from the endosome, 

 divides, the daughter halves separate and occupy positions at the 

 approximate poles of the division figure. From each granule is 

 freed a blepharoplast-basal body complex which becomes the base 

 of the bifurcated flagellum. A chromatoid residue remains on 

 the nuclear membrane, connected by a rhizoplast to the ble- 

 pharoplast and in one animal to the endosome. The residue 

 retains this intimate connection with the motor apparatus until 

 the animals are completely reorganized, at which time it breaks 

 away from the nuclear membrane, the rhizoplasts disappear and 

 it passes into the cytoplasm. As the next mitosis approaches, it 

 begins to degenerate as a rule, and finally disappears entirely. 



