I 



182 BOTANICAL GAZETTE [march 



average coefficient of 1.47 per degree Centigrade. I have calcu- 

 lated his data according to formula 2 and find the value of Qi to 

 vary from 5 to 88. There is a definite break in his data which pre- 

 vents them from falling on a smooth curve. This is probably 

 due to some uncontrolled factor in experimentation. I find that 

 the data in other articles cited here, both on life duration and 

 coagulation of proteins, give smooth curves. 



The Qio coefficient for life duration of animals, so far as worked, 

 is very much larger than for plants. Loeb (23) found a Qi value 

 varying from 240 to 1450 for fertilized sea urchin eggs, while for 

 unfertilized eggs he found a value of 600. Moore (24) found a 



Qio value varying from 485 to 3900 for the stems of Tubular ia 

 crocea. 



The Qio value for the coagulation of proteins shows a wide 



a 



variation for the various proteins or different conditions of the same 

 protein as calculated by Kanitz (20). Chick and Martin (12) 

 found a value of 14 for haemoglobin and 635 for egg albumen. I 

 have calculated the value of Qi for Buglia's (7) data and find it 

 to be about 15 for blood serum, 760 for fresh muscle, 45 for neutral 

 albumen, and 240 for neutral concentrated albumen. 



The low Qio coefficients found for plants mean that they can 

 endure various supramaximal temperatures for relatively long 

 periods as compared with animals with the larger Q I0 coefficients. 

 This may be of great importance to plants, since in many habitats 

 they are unable to avoid intense radiant energy. The radiant 

 energy is largely absorbed and the plants attain temperatures as 

 much as 2 8° C. above the air temperatures, and certainly several 

 degrees above the maximal for growth (2, 6, 26, 30). In general 

 the animal is able to avoid such superheating through locomotion. 

 As bearing on this point many more determinations are needed 

 both on animals and on plants of a variety of habits and habitats. 



The difference between the temperature coefficients for plants 

 and animals shows itself in an experimental way. There is the 

 possibility of employing a much greater range of temperature in 

 plant material. In the investigations on animals previously 

 cited the range used is about io° C, while in investigations on 

 plants the range is 20 C. or more. In plants a much greater range 





