228 VnivcrsUij of California Publications in Zoology [Vol. 16 



has already been pointed out, he considered it nuclear in nature and 

 not a centrosome. Hartmann and Prowazek (1907) employed the 

 same name, but claimed for the structure both ceutrosomic and nuclear 

 value. 



The term kinetonuclcus was first employed by Woodcock. As the 

 word indicates, he is convinced of its nuclear value, terming it the 

 nucleus which controls the kinetic functions (1906). In this opinion 

 Minchin agrees, as do also the majority of English investigators. 

 Without elaborating his reasons for his conclusions, Minchin (1908) 

 states that this structure "is a distinct kinetic nucleus, a specializa- 

 tion of the nuclear apparatus for a particular function.". He later 

 (1912) gives his views on the origin of the kinetonuclcus as a division 

 of the original nucleus into two nuclei of unequal size, and empha- 

 sizes its essential nuclear nature and function. 



In a more recent memoir (Minchin and Thomson, 1915), giving 

 what is, by far, the most complete account of the trypanosorae life- 

 cycle to date, no evidence is given to show that the parabasal body 

 ever arises by a division of the nucleus, since, indeed, it is figured as 

 a permanent structure in all stages of the life-history. Nor has any 

 other investigator been more successful in bringing forward proofs 

 for these claims, which rest solely upon the work of Schaudinn (1904). 

 As has already been pointed out, these conclusions of Schaudinn 's are 

 based on erroneous interpretations of accidental appearances in in- 

 dividuals of two different species. The so-called mitotic figures of 

 the parabasal bodies in division, have, in nearly every case, been 

 shown to be accidental appearances in a cell which otherwise shows 

 no evidence of division. Wherever other evidences of cell-division 

 are present, the division of the parabasal body is almost invariably 

 figured as a simple constriction. 



The origin of the parabasal body by an unequal heteropole 

 division of the nucleus is another claim for which the evidence is very 

 slight, if indeed there is any beyond serious criticism, in spite of the 

 attempts of Neumann (1909) and Berliner (1909) to figure this 

 process in the Haemosporidia, where the entire absence of a motor 

 apparatus is one of the characteristic features of its morphology. 



Alexeieff (1910) has pointed out the lack of nuclear and centrosomic 

 value of the parabasal body of Trypanoplasma, giving as his reasons 

 the fact that it is often composed of several pieces, presents no definite 

 structure, and does not divide mitotically. For its probable function 

 he suggests that it may be composed of reserve material for the motor 



