82 



THE PROTOZOA 



the kinetic activities of the nucleus, a function which may be re- 

 garded as its primary and most characteristic role. It may act 

 also, however, as the centre of other kinetic functions of the cell- 

 body, especially in relation to motile organs such as flagella ; it 

 then appears as the so-called " basal granule," from which the 

 flagella take origin. The basal granule appears as a thickening 

 at the base of the flagellum. It may be continued farther into 

 the cytoplasm, or connected with the nucleus, by means of one 



or more root-like processes known 

 as the rhizoplast. A centrosome 

 which is in relation to a motor 

 cell-organ is termed generally a 

 blepharoplast. The rhizoplast may 

 ."" have various origins-; in some cases 

 it represents the centrodesmose 

 {p. 103) which connects the bleph- 

 aroplast with the nuclear centro- 

 some, or the remains of such a 

 connection ; in other cases it repre- 

 sents the remains of the nuclear 

 spindle of the previous nuclear 

 division, as in the swarm-spores of 

 Stemonitis ftaccida (Jahn, 69) and 



FIG. 38. Mastigina setosa, after Gold- 

 schmidt (41). n., Nucleus from which 

 the long flagellum arises ; the body 

 is full of diatoms and other food- 

 bodies. The surface of the body has a 

 covering of short bristle-like processes. 



ABC 



FIG. 39. Connection of the flagellum 

 and the nucleus in Mastigina setosa. 

 A and B, As seen in the living 

 state ; 0, after fixation and staining. 

 After Goldschmidt (41). 



the collar-cells of Heterocoela (Robertson, 79) ; while in some 

 instances it may be formed by outgrowth of root-like processes, 

 of no special cytological significance, from^the blepharoplast. 



The relation of the nuclear to the kinetic apparatus is best 

 studied in the Flagellata, where three principal conditions may be 

 distinguished as follows : 



1. The cell-body contains but a single centrosome, which functions 

 also as a blepharoplast ; these two names, then, denote two different 

 phases of activity of one and the same body, whieh is a centro- 



