TRICHOMONAD FLAGELLATES. 343 



point. The blepharoplast is exceptionally large. We have not found 

 it separating in this species into centrosome and basal granule as in 

 Trichomonas augusta and T. muris. 



Binary Fission. 



No attempt has been made by us to find the full history of binary 

 fission in this species since it differs so slightly in organization from 

 Trichomonas augusta which we have described so fully. It presents 

 certain obvious disadvantages for such study, namely the absence of 

 axostylar chromidia, the abundance of vacuoles filled with solid food 

 obscuring structure (PI. 6, Figs. 67, 69), and the smaller size. We 

 therefore present no data on binary fission in this species except to 

 note that the four flagella are shared two and two by the daughter 

 blepharoplasts at mitosis (Fig. 70). 



Multiple Fission. 



Fortunately this phase occurred in abundance in the large intestine 

 of Diemyctylus torosus in March in hosts which had been scantily fed 

 and retained in the laboratory for four to six weeks after the close of 

 their breeding season. Slides from the intestinal wall contain stages 

 both of the formation and of the disintegration of the plasmodium or 

 somatella (PL 6, Figs. 70-78). 



The formation of the 8-nucleate plasmodium results from three 

 successive completely pervading mitoses (PI. 6, Figs. 70-72) without 

 plasmotomy. The nuclei at the close of the process (Fig. 71) have 

 a single central karyosome and an intranuclear chromidial cloud. 

 Later the karyosome disappears and fine chromatic granules are dis- 

 tributed throughout the nucleus (Fig. 72). The blepharoplasts are 

 peripherally located and the undulating membranes terminate near 

 the middle when the organism is on the substrate (Fig. 72). The 

 axostyles are not readily found in these stages because of their small 

 size and when present are easily confused with the elongated cyto- 

 stome (Fig. 72). 



The disintegrative phases are readily distinguished from those in 

 the formative process in all cases of odd number of nuclei but not in 

 the case of the even number when the nuclei are in the resting condi- 

 tion, especially from the 2- and 4-nucleate stages. Dispersal of the 



