214 L. R. CLEVELAND. 



are many reasons for thinking that the protozoa digest the wood 

 for their host. In Reticulitermes flavipes practically all the wood 

 particles which reach the hind-intestine are immediately ingested 

 by the protozoa. Hundreds of individuals of this species have 

 been examined to note if wood particles were ever present in a 

 very great quantity in the intestine, and in only a few instances 

 were they ever found in abundance. Perhaps, directly after the 

 termite has taken a meal, wood particles may be quite plentiful, 

 in the intestine, but it is certainly not long before nearly all of 

 these particles of w r ood are taken into the bodies of the protozoa. 

 In Termopsis many wood particles are free in the intestine, though 

 the wood ingesting protozoa harbored by this genus always have 

 their bodies filled with wood particles to the same extent as do 

 the wood ingesting protozoa harbored by Reticulitermes. Quite 

 a bit of woody material is present in the expressed pellets of 

 excrement of Termopsis, whereas Reticulitermes, on the contrary 

 has a liquid excrement. 



Of course the mere fact that the protozoa take the particles 

 of wood into their bodies does not mean that they in any way 

 alter these substances, for many protozoa ingest substances 

 which they cannot use as food. Not all of the termite protozoa 

 ingest solid particles of wood for food, or at all, though most of 

 them do. Among the protozoa harbored by Termopsis sp., of 

 Ashland, Oregon, Streblomastix strix does not ingest the wood 

 particles, and this organism never gives a glycogen reaction. 

 Streblomastix strix, then, may get its nourishment from the diges- 

 tion products of the other protozoa which Termopsis harbors, 

 such as Trichonympha campanula, which ingests great quantities 

 of wood particles and always gives a very clear cut and definite 

 glycogen reaction, provided its host has not been wood starved; 

 or it may derive its nourishment directly from the products which 

 its host has assimilated, in which case it is a true parasite. If 

 this protozoon gets its noruishment from the digestion products 

 of other protozoa present in the intestine of its host, just in the 

 same way that the termite gets its nourishment, Streblomastix 

 strix, then, may be a commensal from the viewpoint of the ter- 

 mite, but from the viewpoint of its relation to the wood digesting 

 protozoa, it is a true parasite, since it in no way aids the wood 

 digesting protozoa, whereas the termite does aid them since it 



