454 



of very fine chromatin granules lying between it and the nuclear wall 

 (figure 2). 



I have been able to examine a large number of dividing forms, and 

 as it is so frequently the case in these rather complicated flagellates the 

 order of the division of the various structures does not seem to be ab- 

 solutely constant. Attention has been drawn to the same point in a 

 paper Miss Robertson and I published recently in the Quarterly Jour- 

 nal of Microscopical Science on the Coecal Parasites of Fowls. (Q. J.M. S.) 



As this is the case it seems more convenient to describe the behavior 

 during division of each structure in turn rather than describe the ap- 

 pearances of a series of individuals. 



The Flagella: — Early in division one basal granule with its cor- 

 responding flagellum moves across to the other side of the animal. At 



Fig. 1. 



Fig. 2. Fig. 3. 



All figures were drawn at Table level with Zeiss Apt. 1 — 5 and Comp. oc. 18. 



Figure 1. Normal active form of Proivazekia terricola showing flagella, kineto- 



nucleus and trophonucleus. 



Figure 2. Condensation of the Chromatin in the Trophonucleus preparatory to 



division. 

 Figure 3. Early change of division showing division of kinetonucleus. 



a slightly later stage it is found that this flagellum has split, so that each 

 of the future daughter individuals will possess their normal number of 

 flagella (see figures 3 — 5). 



The Kinetonucleus: — During the early stages of division the 

 kinetonucleus swells and the contained chromatin has the appearance 

 of a number of distinct granules. During division I have never been 

 able to find any trace of anything corresponding to the mitotic pheno- 

 mena of an ordinary nuclear division. As will be seen from the figures, 

 all that happens appears to be that part of the kinetonucleus streams 



