4.3
regard them as involution forms.
my own cultures they show a distinct and well staining nucleus with apposed deeply coloured centrosome. They display a distinct tendency to division. In many cases they also show a distinct undulating membrane (Fig. 3). From my investigations they would not appear to represent forms of resistance - Encysted forms - as suggested by Pouwen, Thiroux, and Bonet. In older cultures they are for the most part absent. From what I have seen, they would appear to represent young forms of the trypanosoma, which under certain circumstances develop into the mature parasite. Forms similar to these have not been observed in the blood of the frog itself, although in the case of other trypanosomes they are often found in the spleen, e.g., the Nagana parasite in the rat.
They are rare according to William Hunter.