84 



THE PROTOZOA 



In the first place, the flagellum or flagella may disappear, together 

 with their blepharoplasts ; the nuclear centrosome divides into 

 two, which control the division of the nucleus in the usual way, and 

 the centrosome of each daughter-nucleus divides again into two, 

 one of which is the definitive centrosome, the other the blepharo- 

 plast, of the daughter-cell. The new flagella may either grow out 

 from the daughter-centrosomes before they divide, and be carried 

 off, as it were, by the product of division which becomes the 



FIG. 41. Stages in the division of Spongomonas splendida, to show different ways 

 in which the daughter-flagella arise. Compare the stages of S. uvella (Fig. 42). 

 A, Resting condition of the cell. B, Early stage of mitosis; the two flagella 

 of the parent cell are in process of absorption, together with their blepharo- 

 plasts. G, Daughter-flagella arising at the poles of the nuclear spindle ; the 

 flagella of the parent have disappeared. D, Nucleus completely divided ; 

 one pair of daughter-flagella are seen arising from the karyosome of a daughter- 

 nucleus, in which the blepharoplasts are still enclosed ; in the other daughter- 

 nucleus the blepharoplasts have become distinct and the flagella are given 

 off from them. E, Similar stage ; the two pairs of blepharoplasts, from which 

 the flagella arise, are quite independent of the two daughter-nuclei. After 

 Hartmann and Chagas (62), magnification about 2,400 diameters. 



blepharoplast (Fig. 41, C, D, E ; Fig. 42, C), or they may not arise 

 from the blepharoplasts until a later period, after they have 

 separated off from the definitive centrosomes (Fig. 42, D, E, F). 

 The examples figured show that these differences in the origin of 

 the flagella may occur as developmental variations in one and the 

 same species. 



In the second place, the blepharoplasts and flagella"may persist 

 throughout the division of the cell ; then either the old flagellum 

 and blepharoplast are retained by one daughter-cell, while the other 



