204 L - R - CLEVELAND. 



After the incubated and defaunated termites had been fed 

 humus and kept alive for a longer period of time than they would 

 have lived had they been fed wood, as shown by the death of all 

 the wood fed defaunated controls; from time to time transfers 

 back to a wood diet were made, with the result, in each case, of 

 death in ten to twenty days, the usual length of life of wood-fed 

 defaunated termites. The last of the transfers back to wood was 

 made after the defaunated termites had been kept alive, active, 

 and apparently normal in every respect, on a humus diet for 

 three months. Death resulted, as was expected from the pre- 

 vious experiments, and two weeks after all the defaunated ter- 

 mites which had been transferred from the humus to the wood 

 diet were dead, the humus-fed defaunated termites were alive and 

 active, at which time the experiments were discontinued. That 

 progressive development took place is evidenced by the fact that 

 molting occurred in the humus-fed defaunated termites three 

 months after all the protozoa had been removed by incubation. 

 Deeply pigmented first form reproductive adults were formed in 

 several of the jars during December and January. 



From these experiments it is obvious that the humus which was 

 fed to the defaunated termites is potent to prolong their life 

 four months and probably indefinitely beyond the death 

 point of such termites when fed a diet of wood. The unincubated 

 controls, which had been fed wood and kept in the laboratory 

 in the same way as the incubated and defaunated termites being 

 fed wood and the incubated and defaunated termites being fed 

 humus, were alive and active at the time the experiments were 

 discontinued. Now, since the incubated and defaunated ter- 

 mites live indefinitely when fed humus, but die in two to three 

 weeks when fed wood, and the unincubated and faunated termites 

 live indefinitely when fed wood, it is evident that the death of the 

 incubated and defaunated t;ermites is not due directly to the 

 incubation temperature, but to an acquired inability to make use 

 of wood as food. In other words, the termites after incubation 

 and the removal of the protozoa, are no longer able to maintain 

 themselves on their normal diet of wood, and death results. The 

 incubation has in some way incapacitated them as wood users. 

 They feed on the wood, as may easily be determined by watching 

 them or by examining their intestinal contents, but evidently are 



