46 RESEARCH IN PROTOZOOLOGY 



occur later on. In Oxymonas dimorpha from Neotermes simplici- 

 cornis F. C. Connell has found that a flagellated, active form oc- 

 curs in recently molted nymphs and that this later becomes 

 attached, loses its flagella and enlarges. Tricercomitus from Ter- 

 mopsis assumes a different form in the pale nymphs which have 

 recently undergone ecdysis from that which occurs when the 

 normal infection is reestablished. Investigation of the infection at 

 various stages during the stadia of the hosts is essential for a 

 complete understanding of the life histories of the flagellates. 



Until recently, investigators have depended for mitotic figures 

 upon random preparations. Occasionally a slide would be found 

 on which were many stages of division, and one or a few such 

 accidental slides provided material for an account of the process. 

 In some instances, it was found that transferring the termites 

 from their normal diet of wood to one of filter paper stimulated 

 division, so that slides made a few days later contained numerous 

 stages of the process. 



Andrew and Light (1929) have investigated the problem of the 

 occurrence of division stages and discovered methods for obtaining 

 these in much greater abundance than earlier workers found pos- 

 sible. They found that after the fauna has reached its optimum 

 number, it remains fairly constant with a very low reproductive 

 rate and death rate, until the reduction which takes place prior 

 to ecdysis. Following reinfection after ecdysis many division stages 

 occur during the first few days. Tcrmopsis nymphs were isolated 

 after molting and fed the intestinal contents of normally faunated 

 termites. On smears made from these within the first few days 

 after reinfection mitotic figures were numerous. Division stages 

 may be procured by taking termites which show by their colora- 

 tion that they are in the third or fourth days after molting. An- 

 drew and Light state that mitotic figures should be induced by 

 restoration to normal conditions after partial defaunation by 

 starvation, drying, removal of part of the fauna by pressure, heat 

 or oxygenation. In experiments by the writer on Termopsis com- 

 pletely defaunated by oxygenation, division stages of Tricho- 

 nympJia were encountered in from a week to two weeks after 

 placing with normally faunated nymphs. 



Defaunation of termites can be accomplished by several methods 

 discovered by Cleveland, which he has summarized in his paper of 

 1926. The first method he used successfully was incubation, main- 



