W. J. V. OSTERHOUT 147 



and that in sea water these processes are in equilibrium (so that the 

 amount of M remains constant) but that when the tissue is transferred 

 to a solution of sodium chloride M is decomposed faster than it is 

 formed and hence the resistance falls. On replacing the tissue in 

 sea water, M is formed more rapidly than it is decomposed and in 

 consequence the resistance rises. 



Let us assume that when the tissue is transferred from sea water 

 to the solution of NaCl the reactions O -^ S -^ A cease and that the 

 velocity constant K^ of the reaction A —^ M increases from 0.0036 to 

 0.0180 while the velocity constant Kj^ of the reaction M —^B increases 

 from 0.1080 to 0.540. We may then calculate the resistance in the 

 solution of NaCl after any length of exposure by means of the formula^ 



Resistance = 2,700 ( — ) (e~^^^- e~^^^) + 90 e~^^^+ 10 (l) 



\Km - Ka/ \ / 



in which T is the time of exposure in minutes, and e is the basis of 

 natural logarithms. 10 is added in the formula because the base line 

 is taken as 10 (not as 0) for the reason that the resistance sinks to 10 

 ( as shown in Fig. 1) when the tissue dies. 



We assume that when the tissue is replaced in sea water the reac- 

 tions O ^ S —> A recommence and that the values of Ka and Km 

 become 0.0036 and 0.1080 respectively, while the other velocity con- 

 stants likewise acquire the values which they normally have in sea 

 water. Under these conditions M will be formed faster than it is 

 decomposed and the resistance will rise. 



The fact that the rise does not reach as high a level after a long 

 exposure as after a short one indicates that during the exposure 

 gradually diminishes ; we assume that this takes place by the reactions 



N->0-^P 



We likewise assume that during exposure to the solution of NaCl 

 the amount of 6* changes by means of the reactions 



and that on transferring to sea water 5 is rapidly converted into A . 



^ For an explanation of the formula see Osterhout, W. J. V., Proc. Am. Phil. Soc, 

 1916, Iv, 533. The constants 8.853 and 0.2951 are here multiplied by 305, becom- 

 ing 2,700 and 90 respectively. 



