ENERGY SUPPLY OF THE CELL 137 



an incomplete decomposition; quite slow rates at low 

 temperatures decrease but very little, and bring about 

 a practically complete decomposition. 



In living cells, the deterioration of the enzyme in the 

 cell is counteracted by the cell's faculty to produce new 

 enzyme. The normal cell works with a constant enzyme 

 concentration. 



In such a cell, an increase of temperature will increase 

 the rate of fermentation, without any later decrease, 

 until a point is reached where the enzyme deteriorates 

 more rapidly than the cell can replace it. Then, the 

 Tammann principle becomes evident. 



The existence of a true minimum temperature, i.e., 

 a temperature above the freezing point of the medium 

 below which no fermentation can take place, has not 

 as yet been proved. Fermentation will continue at 

 temperatures considerably below the growth minimum. 



(g) CHEMICAL STIMULATION AND INHIBITION OF 

 FERMENTATION 



It is quite generally claimed and has been proved 

 in many instances that some poisons in very small 

 quantities act as stimulants to certain life functions. 

 In 1915, Rahn offered an explanation for this by an 

 analogy between the actions of temperature and of 

 chemical agents. 



In the case of enzyme action, we may assume that the toxic com- 

 pound acts as a catalyst accelerating the action of an enzyme as 

 well as enzyme deterioration. Enzyme action (see p. 126) may be 

 expressed as 



-w = *^(" - ^) 



and under the influence of the catalyst whose concentration may be 

 given as c, the acceleration could be represented by c« where n may 



