April 10, 1914] 



SCIENCE 



545 



resistance at the time t, a is the total amount 

 of change in resistance when the reaction is 

 completed and A; is a constant (called the ve- 

 locity constant) which indicates the speed of 

 the reaction. K the reaction is of the first 

 order (monomolecular) k should come out con- 

 stant provided the temperature be kept con- 

 stant during the reaction. 



In this case a, which represents the total 

 amount of change, is 980 — 320 = 660 ohms, 

 while X repressnts the loss of resistance after 

 10, 20, 30 minutes, etc. In the calculations 

 common logarithms have been employed. It 

 will be seen from the table that h is nearly 

 constant: the variations are no greater than 

 are commonly found in measuring chemical 

 reactions in the test tube.* It is probable that 

 they would have been smaller if the tempera- 

 ture could have been kept perfectly constant. 



The simplest interpretations of this are as 

 follows. We may suppose that the NaCl re- 

 acts with some one substance in the proto- 

 plasm but that so little of the NaCl is used up 

 that its concentration changes but slightly.^ 

 It can be shown by analytical methods that 

 the concentration of the ISTaCl suffers but little 

 change. In all of the experiments more than 

 1,200 c.c. of NaCl .52M were employed to 

 10 c.c. of tissue. 



It should be added that if a series of reac- 

 tions is involved what we measure is practi- 

 cally the rate of the slowest of the series. 



* The most constant value of Tc is obtained when 

 the material is sound and is taken directly from 

 the ocean just before the beginning of the ex- 

 periment. The temperature should not be al- 

 lowed to rise much above that at which the plants 

 have been growing. The fronds should be neither 

 too old nor too yoimg, and should not have repro- 

 ductive organs. Fronds should be selected which 

 have the mechanical properties requisite to cause 

 the disks to lie flat in the apparatus when it is 

 closed, but to separate spontaneously when it is 

 opened. Failure to realize these conditions, as 

 well as other imperfections in technique, may 

 produce irregular fluctuations in the value of fc. 



5 This applies as well if we suppose that the 

 NaCl in uniting displaces some other substance 

 (e. g., CaClj) provided the latter is not allowed 

 to accumulate too much in the solution. 



An alternative interpretation is that the 

 loss of resistance is due to the spontaneous 

 change of some one substance in the proto- 

 plasm, a process which goes on with extreme 

 slowness until catalyzed by the NaCl. This 

 view is of great interest because it implies 

 that the process of death is always going on 

 even in a healthy and growing cell. 



If we suppose the NaCl to act as a catalyzer 

 it may be that the reaction which it accele- 

 rates is the hydrolysis of some substance in 

 the protoplasm. This would behave as a reac- 

 tion of the first order since the concentration 

 of neither the NaCI nor the water would 

 undergo much alteration. The reaction might 

 be compared to the hydrolysis of cane sugar 

 (when catalyzed by acid) which behaves as a 

 reaction of the first order. 



On this view death would be due to the 

 hydrolysis of some substance (probably pro- 

 tein) in the protoplasm. There is a variety 

 of evidence that death is accompanied by such 

 hydrolysis. 



We should not overlook the possibility that 

 the opposite process (dehydration) would give 

 quite the same result. Death is often ac- 

 companied by the coagulation of certain pro- 

 teins. According to some authors coagula- 

 tion involves dehydration while according to 

 others it is a process of hydrolysis.^ 



We may now consider other possible sug- 

 gestions. One is that the progress of the re- 

 action is determined not by the number of 

 substances taking part but by diffusion. The 

 NaOP difl^uses inward (and the other salts 

 outward) rapidly at first, then more and more 

 slowly, thus affording a certain likeness to 

 the curve of a reaction of the first order. The 

 incorrectness of this interpretation is shown 

 by a study of the temperature coeflicient. The 

 temperature coefficient of diffusion is low, the 

 increase in the rate of diffusion being less than 

 30 per cent, for an increase of 10° C. The 

 increase in the velocity of the reaction of 

 NaCl with living protoplasm amounts to over 

 150 per cent, for an increase of 10° C, which 



" The addition or splitting off of H ions would 

 also behave as a reaction of the first order. 



