2Q2 L. R. CLEVELAND. 



open to attack. At any rate, the lignocellulose, subjected to 

 much less drastic treatment, is just as open to attack. 



Everything that has been observed in termites in nature during 

 a year's time, has been observed in these cellulose-fed termites. 

 Many of the nymphs have become sexually mature young adults 

 and have laid a very large number of eggs, which have hatched 

 normally. Larvae from these eggs have grown even more rapidly 

 than those from the eggs of some of the wood-fed controls. In 

 all the experiments, the larvae now present are greater both in 

 number and in actual body weight than those individuals which 

 were present in the beginning. In other words, the total weight 

 of the colony is now more than twice what it was when the 

 experiment was begun. This increase which has taken place on 

 a cellulose diet is as great as that which has taken place on a 

 wood diet. No deaths have occurred. Molting and the forma- 

 tion of winged adults have been observed in each experiment. 

 Cellulose, then, in every noticeable way, has been as nutritious, 

 so far (12 months), as the normal diet of wood. 



DISCUSSION. 



If these insects can maintain themselves in a perfectly normal 

 manner indefinitely on a cellulose diet, they must be able in 

 some way to fix atmospheric nitrogen, which they use in manu- 

 facturing proteins; or else, contrary to the current opinion, 

 they must be able to transform carbohydrates into proteins. 

 These two possibilities are now being investigated from many 

 angles. 



It should be mentioned, for the benefit of those who have not 

 seen the earlier papers of the writer ('230, '236, '240, '250, '256) 

 on the symbiosis between termites and their intestinal protozoa, 

 that termites from which the protozoa have been removed by 

 either of the three methods (incubation, starvation, oxygenation) 

 lose the ability to live on cellulose or on wood. However, when 

 the protozoa are restored, i.e., when the defaunated termites are 

 reinfected, the ability to live on cellulose or on wood is regained. 

 The teeming menagerie of intestinal protozoa which the termites 

 harbor, then, either digest the cellulose in toto or else play a very 

 important part in its digestion. 



