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 



