64 LIBBIE H. HYMAN 



2. Experiments with f or j molecular KNC. By the use of 

 these concentrations I have been able to discover the cause of the 

 rupture of the ectoplasm which has been described in the preced- 

 ing section as the initial effect of the cyanide. Upon the appli- 

 cation of | or ^ molecular cyanide, the animal becomes motion- 

 less as before, but very soon it can be seen that a pseudopodium is 

 beginning to form. This pseudopodium nearly always starts 

 from the posterior end of the amoeba, although sometimes it 

 occurs on the side of a large pseudopodium, that is, in exactly 

 the same places where the ectoplasm first breaks when the stronger 

 concentrations of cyanide are employed. Ss soon as this pseudo- 

 podium appears, it ruptures, and the endoplasm flows out in the 

 same manner as already described; and following these the pre- 

 viously existing pseudopodia disintegrated from their tips inward 

 exactly as when molecular KNC is used. 



As a result of this experiment, which has been repeated a great 

 many times, I have come to the following conclusion. The re- 

 sponse of the amoeba to the strong stimulation of the cyanide is 

 pseudopod formation, and pseudopod formation at the least 

 active part of its body, the part which would be least affected 

 by the reagent. In cyanide of molecular strength, the pseudo- 

 podium does not and can not form but the ectoplasm ruptures 

 at the place where the pseudopodium would appear. This is 

 demonstrated by the fact that in slightly less concentrated solu- 

 tions a pseudopodium actually does appear in exactly the same 

 places where the ectoplasm breaks in molecular KNC. Since, 

 however, no pseudopodium appears in the latter case one is forced 

 to conclude that some internal change precedes pseudopod for- 

 mation, and that this internal change is the same as that which 

 makes protoplasm in general more susceptible to cyanide than it 

 previously was, that is, a metabolic change. This internal change 

 occurs in both concentrations of cyanide, the susceptibility is 

 locally increased, the ectoplasm dissolves away, but in the one 

 case this occurs before a pseudopodium forms while in the other 

 the pseudopodium appears. I believe the observations permit 

 no other interpretation ; and the conclusion is further confirmed by 

 the experiments on the ' shock' reaction of amoeba to be described 

 later. 



