W. J. V. OSTERHOUT 621 



reached and that in consequence Ao = SOM (the value of M being 

 that of the observed resistance less 10). This value of A was taken 

 for the subsequent calculations. During the subsequent exposure 

 to CaCl2 Aq diminished to Ai according to the formula 



, -(0.0018)360 

 Ai — Ao e 



and this value was used in calculating the fall of resistance during 

 the final exposure to NaCl. 



Experiments similar to those shown in Figs. 1, 2, 3, 4, and 5 have 

 been made, in which mixtures of NaCl + CaCl2 have been used in 

 a variety of ways. In this case we employ for the calculations the 

 constants appropriate for each mixture, as given in a preceding 

 paper.® In general the agreement is satisfactory. 



It should be noted that we do not employ new constants to fit 

 these curves but that in every case we use the constants already 

 determined as the result of other and quite different experiments. 

 In view of this the results have a special significance. 



These experiments, and those described in previous papers, seem 

 to afford a sufficient test of the theory. The agreement between the 

 calculated and observed values appears to be satisfactory whenever 

 a sufficiently large number of readings are averaged in arriving at 

 the observed values. 



It is evident that the equations which have been developed enable 

 us to predict the behavior of the tissue under a great variety of 

 conditions. 



The mechanism which has been postulated in developing these 

 equations consists essentially of a series of catenary reactions. There 

 can be no doubt that catenary reactions play a large part in Hfe 

 phenomena and it would seem that the role assigned to them in the 

 present discussion involves no unreasonable assumption. 



It may be desirable to call attention to featurejs of this mechanism 

 which are of general interest from a theoretical viewpoint. It is 

 evident that by means of a simple catenary system we can account 

 for practically all the processes which occur in the organism. If 

 such a system is present in the egg we can easily picture all of the 

 subsequent development as due to this system, without the intro- 



