552 OSTERHOUT— DYNAMICAL THEORY OF ANTAGONISM. 



constant is increased by the salt, the effect passing through a mini- 

 mum, or diminished by the sah, the eft'ect passing through a 

 maximum.^'' 



That catalyzers actually do act in this way is seen when acid 

 catalyzes lipase, the effect of the acid passing through a maximum. 

 It was found by Hoyer^" that when oxalic or sulphuric acid is added 

 to hpase the action of the enzyme was accelerated in proportion to 

 the amount of acid but that above a certain concentration the effect 

 rapidly fell off. 



Future investigations must decide which explanation fits the 

 facts in the majority of cases. 



We have thus reached a quantitative explanation of the results 

 of our experiments. Our explanation indicates that the resistance 

 is proportional to the amount of M which is present in the proto- 

 plasm. It may therefore be of interest to enquire how the substance 

 M determines the resistance. If it is produced at the surface, as 

 we assume, it may form a layer in the surface which offers resist- 

 ance to the passage of ions. The amount of the resistance would 

 then depend on the thickness (and continuity) of the layer. This 

 may also apply to the internal surfaces, such as those of the nucleus, 

 plastids, vacuoles, and microsomes. 



It is evident that whether or not any of these assumptions be 

 accepted certain facts seem to be established. It is clear that there 

 are two processes, one of which produces a rise, the other a fall 

 of resistance, and that their speed may be regulated by NaCl and 

 CaClo. It is extremely probable that these salts enter into chemical 

 combination with some constituent of the protoplasm and it is evi- 

 dent that the compound thus formed might regulate the speed of 

 one or both of these processes. ^^ 



15 In all these explanations it is understood that NaCl and CaCU act in a 

 saturated surface as explained above, so that only the relative proportions 

 are important. 



!•' Hoyer, E., Bcr. dcutsch. chcm. Gcs., 37(2) : 1436, 1904. 



1' It would seem that we can imitate completely the variations in re- 

 sistance which occur in living protoplasm only when we have a system in 

 which a reaction is going on which results in the production of a substance 

 which is comparable to that designated as M in the foregoing discussion. 

 Perhaps this explains why attempts to imitate these effects by experiments on 

 colloids have not been more successful. 



