1919] Kofokl-Swezij: Ti-ichomitus term it id-is 31 



MITOSIS 



Owing to this i)rolongation of the prophase of mitosis in Tricho- 

 mitus trrmiiidis an exceptional opportunity is afforded for a detailed 

 study of the behavior of the neuromotor system during mitosis. This 

 is made possible by reason of the fact that the centroblepharoplast is 

 the center of the neuromotor system and the point of origin of struc- 

 tures and processes playing the main role in mitosis. 



The phases of mitosis recognizable in the division of Trichomitus 

 are those of the metazoan cell, but, as shown in our (1915) discussion 

 on mitosis in trichomonads, considerably differentiated by the associa- 

 tion of the extra-nuclear organelles of the cell in the protozoan from 

 that in the usually simpler metazoan unit. In Trichomitus these 

 differences, in consequence of the massive development of the neuro- 

 motor system, are even more developed than in the other trichomonads. 

 They consist mainly in the sharp separation of centrosome and ble- 

 pharoplast and the excessive prolongation of the prophase. 



The resting stage of Trichomitus has a single nuclear rhizoplast 

 running from the centroblepharoplast to the anterior end of the 

 nucleus where it is attached to the membrane without evidence of 

 enlargement into a centrosome on the nuclear membrane. This rhizo- 

 plast is often very short (fig. A, 1) and is never very long. The 

 nucleus has in this period a dense, coarsely and uniformly granular 

 central chromatin mass in which no polarization or evidence of chro- 

 mosome formation is present. 



The prophase (fig. B; pi. 3, figs. 1, 2, 5-15) is a prolonged one 

 and in it the duplication of the entire neuromotor system takes place 

 by division and outgrowth from the centroblepharoplast. The initial 

 step is the splitting of the centroblepharoplast and the nuclear rhizo- 

 plast (fig. B, 1). It appears in some cases (pi. 3, fig. 1) that the 

 rhizoplast may divide at the nuclear membrane first and split distally 

 towards the centroblepharoplast as though these were directly upon 

 the nuclear membrane at the anterior end of the nucleus. At the 

 same time the centroblepharoplast separates into its constituent centro- 

 some and blepharoplast, with the latter immediately dividing, one 

 granule taking a single flagellum, the new parabasal body and one 

 of the two nuclear I'hizoplasts (fig. B, 1). The granule remaining 

 attached to the old parabasal body takes the remainder of the flagella 

 and the second nuclear rhizoplast. As these two blepharoplasts sepa- 

 rate a thread is drawn out from each attaching them to the centre- 



