TKICHOMONAD FLAGELLATES. 325 



Figs. 29-31), their decrease in size, their rounding up, and their 

 ultimate disappearance as separate chromatic units. Several small 

 karyosomes may be seen in some nuclei towards the end of this process 

 (PI. 3, Figs. 35), but it seems normally to terminate in a nucleus with 

 a single central karyosome (PI. 3, Fig. 34). There is apparently 

 some reduction in the total amount of chromatin, in the form of deeply 

 stained masses in the nucleus during the telophase. 



The division of the axostyle takes place during this process. Con- 

 trary to previously accepted accounts of the origin of this structure, it 

 is neither derived from the centrodesmose nor by new outgrowths from 

 the blepharoplast. It does not wholly disappear at any time during 

 mitosis in Trichomonas augusta but may be located and its outlines 

 traced in carefully stained material examined with apochromatic 

 objective and compensating oculars. The axostylar chromidia are of 

 great assistance in the quick location of the structure and the verifica- 

 tion of its outlines. 



The old axostyle splits longitudinally from the club-shaped antei-ior 

 end to the posterior tip (PI. 3, Figs. 31-35, PI. 4, Fig. 36). Prior to 

 splitting the axostylar chromidia are somewhat more numerous, and 

 are arranged in a single row in its distal half. In several instances 

 (PI. 3, Figs. 31, 34) the chromidia in the distal undivided part are 

 distinctly larger than those in the adjacent daughter axostyles suggest- 

 ing their splitting m situ as the axostyle splits. The forms, sizes 

 (in a few instances only), positions, and numbers of the axostylar 

 chromidia are suggestive of their division or at least of their increase 

 in number prior to and during division of the axostyle. In premitotic 

 and mitotic stages prior to the division of the axostyle (Pis. 1, 2) the 

 range in number of axostylar chromidia in 19 individuals is 18-56 

 and the average 33. After division (PI. 4) the range in 12 individuals 

 is 9-37 and the average only 23. The variation is so great and the 

 numbers in sister axostyles at times so divergent (PI. 4, Fig. 37) that 

 no precise or regular method of multiplication and sharing of the 

 chromidia thus produced between the daughter axostyles can be 

 postulated from the evidence which, however, does indicate compen- 

 sating increase prior to and during binary fission. 



The position of the axostyle prior to its division especially during 

 the metaphase-telophase is exceedingly varied (Pis. 2-4). Whereas 

 in the premitotic phase it is axial in position with the nucleus next to 

 its enlarged anterior end, during this later period this end becomes 

 more or less widely separated from either daughter nucleus, lying 

 even at the opposite pole (Pi. 3, Fig. 30). As the division of the 



