DYNAMICS OF MORPHOGENESIS 201 



Loeb and various others have used the cyanides extensive!}- dur- 

 ing later years as a means of retarding or inhibiting the oxidation 

 processes. 



It is also certain that the planarian in KCN shows a decrease 

 in COs-production as compared with a normal animal. 



At any rate, it is evident that the CN radical affects some of 

 the most fundamental metabohc reactions. Moreover, the fact 

 that the effect of the cyanides varies according to the rate of 

 reaction in the organism suggests that the action is primarily 

 chemical. Apparently the effect of a KCN-solution depends 

 upon the number of chemical bonds in the organism which are 

 opened up in a given length of time; in other words, the higher 

 the rate of reaction, the greater the opportunity for the KCN to 

 produce its effect. 



Apparently the KCN acts by entering the metabolic complex 

 at some point or points and altering certain essential features of 

 it so that it cannot continue. That the point or points of en- 

 trance lie somewhere along the course of the oxidation processes, 

 is the most generally accepted view. 



But how are we to conceive the process of acclimatization to the 

 cyanides? It occurs only in very low concentrations, but that 

 it does occur there can be no doubt. Why does the relation be- 

 tween the capacity for acclimatization and the rate of reaction 

 exist, i.e., why does the individual or piece with the higher rate 

 of reaction become in general more readily and more completely 

 acclimated? It is evident that a metabolic factor is involved in 

 the process of acclimatization, but we are at present far from any 

 real knowledge as to the nature of the process. The relation 

 between the rate of reaction and the degree and rapidity of 

 acclimatization must have a very definite meaning and it may 

 perhaps serve as a basis for further work along this line. 



We have seen that with alcohol, ether, chloretone and benzamid 

 essentially the same relation between physiological resistance and 

 rate of reaction in the animals exists. Since my investigations 

 have had thus far another object, I have not as yet attempted to 

 determine the relations for any very large number of substances, 

 but the occurrence of the same relation between resistance and 



THE JOURNAL OP EXPERIMENTAL ZOOLOGY, VOL. 14, NO. 2 



