H. S. REED 



557 



population at that date. Table V shows a comparison of the growth 

 rates of maize (Hiihner-mais) , with the height, green weight, and dry 

 weight of the plants, recorded at intervals of 7 days. I have deter- 

 mined the value of K, the growth constant, for each measurement and, 

 from the average value of all determinations, have calculated the value 



TABLE V. 



Rate of Growth of Maize. 

 Data taken from Kreusler (Hiihner-mais). 



of X for corresponding values of t, using the tables prepared by Rob- 

 ertson (1910-15) . The average divergence of the three sets of values is 

 not large, particularly in view of the errors above mentioned. The 

 results show a sufficiently good correspondence to inspire confidence 

 in their reliability. 



It will be seen that the growth rate of the maize plants follows the 

 course of an autocatalytic reaction no matter whether we use as a 

 criterion mean height, green weight, or dry weight. Their growth is 

 similar to a chemical reaction in which one of the products of the re- 

 action acts as a catalyst. 



Attention may next be directed to some data recently published 

 (Eckles and Swett) on the growth of heifers. The measurements 



