SOIL PROTOZOA. 313 



to the fact that the flagellates are almost always crowded with 

 deeply staining bacteria which obscure the nuclear elements. 

 The next stage of the trophonucleus which I have certainly made 

 out, is that in the daughter-organisms where the granules have 

 become concentrated again into a central karyosome separated 

 from the nuclear membrane by a clear zone (fig. 21). Whilst 

 the above changes are proceeding, the kinetonucleus undergoes 

 certain altei'ations. It increases in volume, and may either be 

 triangular or rhomboidal in outline. One pair of flagella moves 

 to either side of it, and at these points the kinetonucleus 

 becomes somewhat drawn out. Soon after the formation of 

 da,ughter-trophonuclei has taken place, the kinetonucleus elon- 

 gates considerably, so that the paii'S of flagella are cai-ried farther 

 apart. This elongation is carried on until a fairly long band of 

 kinetonuclear material is produced, which flnally separates into 

 two portions — the daughter-kinetonuclei. I have not found the 

 stages showing the constriction and division of the kinetonucleus, 

 but there can be no doubt, I think, that the process is simple and 

 direct. 



Concurrently with the elongation of the kinetonucleus, the 

 body of the flagellate becomes oval and then grows laterall}^, so 

 that the longer axis of the body is that running from side to side, 

 not antero-posteriorly. Division of the body is initiated by the 

 formation of a constriction on the now shorter axis of the body, 

 and becomes more and more pronounced until the two daughter- 

 organisms are connected only by a, short narrow strand of proto- 

 plasm. This finally breaks, and the two small organisms are 

 produced. Division thus takes place along the antero-posterior 

 axis of the body, and is therefore longitudinal. 



- (c) Systematic Position. 



Because of the rapid spasmodic jumping motion exhibited by 

 this organism in life, the name saltans is eminently applicable to 

 it. From its general shape also, and the presence of two flagella, 

 the posterior one being longer than the anterior, it easily fits into 

 the genus Bodo. The difficult point to determine, however, is 

 whether it should be classified as a Bodo or as a Proivazekia, for it 

 possesses a kinetonucleus. 



AlexeiefF ('11 k '12) is of the opinion that all the species of 

 Bodo possess a kinetonucleus, and holds that the genus Pro^wt^eZ;/* 

 is uiitenable. According to this author, my organism should go in 

 the genus Bodo. I am not convinced, however, that his assertion 

 concerning the presence of a kinetonucleus in Bodo is correct, for 

 I have obtained a bimastigote form having the anterior flagellum 

 shorter than the posterior one in which there is certainly no kineto- 

 nucleus, and which undoubtedly belongs to the genus Bodo. I 

 therefore propose to place my organism in the genus Prowazelcia. 

 At the same time, however, I insert the name Bodo in In-ackets, 

 because I think this form is identical with Bodo saltans. Alexeieff 



