DYNAMICS OF MORPHOGENESIS 185 



the temperature coefficient of the rate of chemical reaction in the 

 organism is of the same order of magnitude as that found for many 

 other chemical reactions then the rate of reaction in the organism 

 must increase two to three times with a rise of 10°C. On the 

 other hand, according to Meyer, the coefficient of distribution 

 decreases only about one-third with a rise of about 30°C. In 

 short the temperature changes in the rate of chemical reaction 

 are so much greater than those of the coefficient of distribution 

 that it is difficult to understand why the first factor does not 

 overbalance and mask the second. For example, in 0.02 m. 

 benzamid the animals are narcotized both at 10° and at 20°, 

 but more rapidly at 10° and they also die earlier at 10°. Evi- 

 dently at 10° enough benzamid enters the cell to produce the 

 full physiological effect. At 20° the coefficient of distribution 

 is only very slightlj^ lower than at 10°, but the rate of reaction in 

 the organism is supposedly two to three times as great as at 10°. 

 The temperature coefficient of distribution of benzamid for 10°C. 

 is so small that it cannot possibly account for the observed 

 results which are constant and distinct. 



There can be little doubt, I think, that with sufficiently low 

 concentrations of benzamid the increase in rate of reaction in the 

 organism is the chief factor in determining that the narcotic effect 

 is less at the higher than at the lower temperature. At 10° the 

 rate of reaction is so low that the concentration of benzamid in 

 the cell is sufficient to produce the full physiological effect: at 

 20° the concentration in the cell as determined by the coefficient 

 of distribution is only very slightly lower, but the rate of reaction 

 in the animal is now two to three times as great as before, i.e., 

 it is now so great as compared with the concentration of benzamid 

 in the cell that only a fraction of the total reaction volume can 

 be affected by the benzamid, consequently the physiological 

 effect is less at the higher than at the lower temperature. 



And. here the factor of acclimatization enters. We have seen 

 that for KCN and alcohol, the higher the rate of reaction, the 

 greater the degree of acclimatization, provided the concentration 

 of the reagent is sufficiently low. The same rule holds good for 

 benzamid. In this case it is impossible to determine where the 



THE JOUKNAL OF EXPERIMENTAL ZOOLOOT, VOL. 14, NO. 2 



