250 
New Protist Parasites 
often half-way down the axostyle (Figs. 1 and 2). In this way the 
connection between the basal granules and the axostyle is left very 
clear. The axostyle generally appears to run through the nucleus, or is 
very closely applied to it: in a few instances, however (Fig. 3), I found 
specimens in which the nucleus had been shifted out of its normal 
median position, and the axostyle lay exposed for its entire length. 
I saw no differentiation into forms with thin and forms with thick 
axostyles, such as Dobell describes for T. batrachorum. 
Division stages are very difficult to find, and it is only after 
prolonged searching that I have been able to collect the series shown in 
Figs. 4 to 10. It will be seen that they agree in all essentials with the 
figures given by Prowazek and Dobell. I am in agreement with Dobell 
in thinking that the axostyle is withdrawn and absorbed, and is then 
reconstructed from the basal granules in the process of division. The 
early division stages show this quite clearly. The nuclear membrane 
disajDpears; the chromatin collects into large, irregular masses; the 
basal granules separate, and form the poles of the spindle on which the 
chromatin becomes divided into two portions. At this point the body 
of the organism shows a median constriction, which deepens until the 
two halves are hanging together by a thin strand. The final stages of 
division are rare in my preparations, but Fig. 10 shows the daughter 
flagellates in the act of separating. It is very difficult to make out the 
fate of the flagella during this process. Apparently, two go over with 
each basal granule, where two new are then formed afresh for each 
individual. Figs. 6, 7 and 8 show the new flagella sprouting. I cannot 
say for certain what happens to the cytostome. From Fig. 10 it would 
seem that the old cytostome goes over into one of the daughter 
flagellates, while the other must form a new one for itself. 
The cytoplasm shows a very clear mesh-work structure of varying 
coarseness. It often contains darkly staining granules and bacterial 
masses. 
I have never seen cysts of the type described by Dobell for 
T. batrachorum. After long search I found in four preparations a 
few instances of what appear to me to be stages iu the encystment 
of Trichomastix trichopterae, though I must admit that, without 
observation of the living cyst, it is dangerous to be dogmatic. As 
Dobell (1908) lias recently emphasized, there is a risk of confusing 
with true cysts yeast-cells or other organisms present in the intestinal 
contents. Figs. 12 to 15 illustrate the objects to which I refer. They 
bear a striking resemblance, at any rate, to encapsuled organisms of the 
