1919] Kofokl-Swezy : Trichomitus termiiidis 27 



stance. This centroblepharoplast is thus most truly a morphological 

 center intimately associated with the motor organs of this cell and 

 their activities during the vegetative phase. At mitosis it dominates 

 not only the extra-nuclear neuromotor system but also the polarization 

 and subsequent movements of the chromosomes within the nucleus 

 (fig. B, and pi. 3, figs. 5-21) as well. It will be difficult to find in 

 any metazoan cell so continuous and complete a control, so pervasive 

 an influence vipon cell activities by the cell organ there known as the 

 centrosome, as we find by the centroblepharoplast in Trichomitus. 



The centroblepharoplast, during the vegetative phase of Tricho- 

 mitus (fig. A, 6), is a minute gi-auule about a micron in diameter 

 anterior to the nucleus and attached to the anterior end of a single 

 nuclear rhizoplast (fig. A, 5, n. rh.; fig. A, 2). This rhizoplast is a 

 delicate thread easily overlooked. The centroblepharoplast itself is 

 imbedded in the end of the deeply staining parabasal body, and may 

 likewise readily escape detection. 



In view of its later history it seems advisable to designate this 

 granule at this period as the centroblepharoplast, since from it emerges 

 the parent centrosome at mitosis. There is, however, no duplicity of 

 structure evident, and there is no granule at any time at the point 

 where the nuclear rhizoplast passing from the centroblepharoplast 

 (fig. B, 1) and later from the blepharoplast proper (fig. B, 5) meets 

 the nuclear membrane. After the centrosome withdraws from the 

 larger granule (fig. B; pi. 3, figs. 6-21), the latter becomes a ble- 

 pharoplast in the restricted sense of a basal granule from which the 

 flagella originate, having no other function in mitosis, whereas the 

 centrosome emerging from it divides and its daughters form the 

 paradesmose between them, assume a polar position thereon and move 

 to the nucleus (fig. B; pi. 3, fig. 21). 



In our investigations of mitosis in the trichomonads (1915, pi. 2, 

 figs. 21, 23; pi. 3, figs. 24, 29) there appeared to be a separation of 

 the polar centrosome-blepharoplast into two granules, one of which, 

 the centrosome, remained in the polar position on the nucleus, and 

 the other, the blepharoplast, usually with the flagella attached, was 

 removed a short distance therefrom. The conditions which we have 

 found in Trichomitus where there is a general, more complete and 

 perfectly distinct separation of these two organelles is thus the full 

 accomplishment of the segregation imperfectly realized in Tricho- 

 monas. 



The flagella are four in number, the three undifferentiated, equal, 

 anterior ones (fig. A, 5, ant. ft.) and the attached posteriorly directed 



