SELIG HECHT 675 



that the substance T, formed during the latent period, is thermo- 

 labile, it is possible to account quantitatively for the activity of this 

 second factor. A certain amount of T must be formed in order 

 that a response of Mya may result. If some of this material T is 

 destroyed at temperatures above 21°, the latent period reaction, 

 L-^T, must proceed longer in order to make up the amount of T 

 necessary for a response. As the temperature increases, the rate of 

 destruction of the thermolabile substance T will also increase. Con- 

 sequently the latent period reaction will have to proceed longer in 

 order to make up the required quantity of T. The disparity between 

 calculated curve and actual results will therefore become greater and 

 greater. 



If this reasoning is correct, it should be possible to determine 

 quantitatively not only the effect of this destructive second factor, 

 but the nature and dynamics of the process as well. 



IV. 



The work of Chick and Martin (1911) has demonstrated that the 

 rate of heat coagulation of hemoglobin and of egg albumin may best 

 be represented by the course of a reaction of the first order. More 

 pertinent, perhaps, are the experiments of Madsen (Arrhenius, 1915) 

 in which it was found that the spontaneous decomposition or inacti- 

 vation of many thermolabile substances also follows the course of a 

 monomolecular chemical reaction. It is therefore reasonable to as- 

 sume that the destruction of our thermolabile substance T into some 

 ineffective material iV also follows the course of a monomolecular 

 reaction. For the sake of simpUcity let it be further assumed that the 

 latent period reaction itself, L^T, is also a reaction of the first 

 order. The duration of the latent period at temperatures above 21° 

 may thus be considered to depend upon two reactions, 



L— >r, r— >iV 



forming a catenary system. From this reaction system a certain 

 quantity of the substance T must accumulate in the sense organ 

 before a response on the part of Mya can result. 



The quantitative relations of these two reactions may be illustrated 



