UPON ELECTRICAL STIMULI GENERALLY 55 



downwards a supply of oxygen may be assured to the 

 seedling. 



Now carbon has great affinity for oxygen, will readily 

 absorb it and give it out again under the pressure of water. 

 This, no doubt, is the reason why, taught by experience, 

 gardeners place pieces of charcoal in the soil of the pot. 



Bose, whose work to me possesses only academic interest, 

 inasmuch as I am dense enough to fail to see its practical 

 application, says that " one mode of increasing the internal 

 energy of a plant is by a moderate rise of temperature . . . 

 a steady rise of temperature brings about an increase of 

 internal energy, while a sudden variation of temperature 

 acts as a stimulus. Thus, if we e£Fect a sudden augmenta- 

 tion of temperature, this will act upon the organ, during 

 the period of variation, as a stimulus ; but afterwards, 

 when the temperature itself, or its rate of rise, has become 

 steady, the condition will act by increasing the internal 

 energy of the organ." 



I have the greatest possible respect for Professor Bose 

 (Comparative Electro-Physiology), but while the effect of a 

 rise of temperature may appear to increase the internal 

 energy of a plant, it does not, strictly speaking, do so ; 

 the energy is there all the time. What it does do is to induce 

 an increased flow of energy by reducing the internal resistance 

 of the plant. 



It is, I think, a false conclusion to come to, and false 

 conclusions lie at the root of mistaken theory. The student 

 might be led to believe that the additional energy alleged 

 to be imparted to the plant was contained in heat, whereas 

 the phenomenon was due to decreased resistance and not to 

 augmented pressure. 



The Table given (page 430) of " The Effect of rise of 

 Temperature on Velocity " (of transmission of electrical 

 impulse) sufficiently shows this : 



At 30°c. the velocity was 3.7 mm. ; at 35°c., 7.4 

 mm., and at 37°c., 9.1 mm. per second. 



Increase of energy, or of flow, is a secondary, not a 

 primary consequence of rise of temperature and if instead 



