SOCIAL TRANSITIONS 269 



nymphs may develop into the winged reproductives 

 that swarm forth in the nuptial flight. 



As many know, most termites eat wood which, 

 paradoxically enough, they are unable to digest 

 although they do obtain their nourishment from it. 

 The answer to this riddle is that the termites harbor 

 in their alimentary canals several species of flagel- 

 late protozoans which can and do change the wood 

 into substances which both termites and these flagel- 

 lates find highly nutritious. 



From many structural relationships we know that 

 termites are close relatives of cockroaches, and studies 

 by Dr. Cleveland of Harvard (34) have shown how 

 the termite societies may have arisen from the much 

 less social cockroaches. Here we have an example of 

 one of the many possible connections between highly 

 developed social life and the less social state illus- 

 trated by the mass physiology characteristic of animal 

 aggregations. 



Cryptocercus is a wood-eating cockroach which is 

 found in decaying wood of the forests of the Ap- 

 palachian mountains from Pennsylvania to Georgia, 

 and along the coastal mountains in the northwestern 

 part of the United States. Like their relatives, the 

 termites, these cockroaches feed on wood, and also 

 like the termites they harbor wood-digesting pro- 

 tozoans in their alimentary tract. These wood roaches 



