ISO L. R. CLEVELAND. 



numbers of protozoa. It is not definitely known why protozoa 

 are never found in the intestine of any of the Termitidae; but a 

 difference in the feeding habit has been suggested as a very prob- 

 able explanation, since few, if any, of the Termitidae feed solely 

 on wood. 



THE PROBLEM. 



To determine the relation of the intestinal protozoa of termites 

 to their host. 



Experimental methods were the paramount mode of attack; 

 and it was necessary, in order to solve the large problem stated 

 above, to solve several problems, which may be briefly stated as 

 follows: 



1. What is the principal compound in wood, the sole article of 

 diet of most termites, which is used for food. 



2. How do termites utilize cellulose, the principal compound 

 in wood, as their chief article of food? 



3. How may all of the intestinal protozoa be killed without at 

 the same time injuring their host? To develop a rapid and suc- 

 cessful method for removing the protozoa from the termites was 

 a very difficult proposition. 



4. Why do termites, when subjected to a temperature of 36 

 C. for 24 hours, lose their ability to maintain themselves on a 

 wood diet? 



5. Is clefaunation (the removal of the protozoan fauna), 

 which occurs when termites are incubated at 36 C. for 24 hours, 

 in any way responsible for the inability of the termites to main- 

 tain themselves on a wood diet? 



6. Why do the incubated and defaunated termites live indef- 

 initely when fed the decomposition products of wood, or the 

 products of fungus-digested cellulose; but die within 1020 days 

 when fed wood, their normal diet, or when fed cellulose? 



7. Why do the incubated and defaunated termites regain 

 their ability to make use of wood or pure cellulose as food when 

 reinfected (refaunated) with protozoa? 



8. Do the unincubated and faunated termites harbor any in- 



phology of Termites and the Presence of Intestinal Protozoa," for a list of the 

 genera and species that have been examined. Since writing this more than 75 

 species of the Termitidae have been examined and three of this number have been 

 found to harbor protozoa and feed on wood. 



