84 



INTRODUCTION TO CYTOLOGY 



described by Dangeard (1901), and finds the elaborate organization 



shown in Fig. 24. 



In a third series of forms two nuclei are present : a principal or trophic 



nucleus and an accessory or kinetic 

 nucleus. Here there are apparently 

 three conditions : (a) a single centrosome, 

 associated with the kinetonucleus, acts 

 both as a blepharoplast and as a division 

 center; (6) usually both nuclei have 

 centrosomes associated with them, the 



FIG. 24. FIG. 25. 



FIG. 24. Diagram of structure of Polytoma uvella. (After Entz, 1918.) 

 a, end-piece of flagellum. b, uniform portion of flagellum. c, lateronema. d, baso- 

 plast or basal granule, e, contractile vacuole. /, cell envelope, g, eyespot. h, rhizonema. 

 i, karyoplast or anchoring granule, j, centronema. k, nucleolus. I, nuclear membrane. 

 m, starch, n, surface of protoplast. 



FIG. 25. Trypanosoma theileri. 



A, flagellum inserted on basal granule. B, formation of new flagellum from daughter 

 basal granule after division; nucleus dividing. (After Hartmann and Noller, 1918.) 



one lying near or within the kinetonucleus acting as the blepharoplast; 

 (c) it is possible that in some cases there is a blepharoplast distinct from 

 the centrosomes accompanying the two nuclei. 



In the trypanosomes (Fig. 25) the recent researches of Kuczynski 

 (1917) and Hartmann and Noller (1918) have shown that the flagellum 



