194 L - R - CLEVELAND. 



In order to establish the fact that the protozoa are symbionts, 

 rather than commensals (feeding from the same table as their 

 host), it must be shown that they actually aid their host in some 

 way by doing something for the host which the host itself cannot 

 do. The experiments of Buscalioni and Comes do not in any way 

 fulfill this condition. They have only shown that the protozoa 

 digest wood particles. The ability or inability of the termites to 

 do the same thing was not studied. That the termites aid the 

 protozoa, by furnishing them food and lodging, is obviously 

 demonstrated by the fact that the protozoa, so far as known, 

 cannot live outside of termites. But w r e cannot call the protozoa 

 symbionts, until their ability to digest wood has been shown to 

 be a necessary aid to the termite. 



Realizing the difficulty of determining the relation of the 

 protozoa to the termites so long as the two were associated to- 

 gether, several experiments were begun, with the hope of effect- 

 ing a method for removing the protozoa from their host, and at 

 the same time leave the host uninjured. It is needless to say that 

 hundreds of experiments some of which are given in Table I. 

 met with failure, for the host was either killed or severely in- 

 jured in an effort to remove the protozoa from it. 



When wood, previously soaked in a 5 per cent, aqueous solu- 

 tion of either sodium, potassium or calcium chloride, was fed to 

 a colony of Reticulitermes flavipes (elsewhere in this paper unless 

 it is otherwise evident when the words "termite," "termites" 

 and "host" are used they refer particularly to this termite) 

 harboring protozoa, within four to five days an occasional ter- 

 mite, free, or almost free, of protozoa was found, when many 

 individuals from the colony w r ere examined. The number free of 

 protozoa increased as time progressed but, before all the termites 

 in the colony had lost their protozoa, it was quite evident that the 

 termites themselves were not normal. They had in some \vay 

 been affected ; whether by a direct action of the chemicals or by a 

 gradual loss of the protozoa, it is impossible to say from the data 

 available. 



About this time a much more promising method for removing 

 the protozoa was evolved; namely, the incubation method, and 

 the experiments employing the use of salts, etc. (see Table I.), 

 to remove the protozoa, were discontinued. It might be well to 



