292 THE SURVIVAL OF THE UNLIKE. LXVII. 



of all the [yearly] positive temperatures of both 

 places."* In order to construct an actual numerical 

 constant or aliquote, Linsser lays down the following 

 rule : ' ' The velocities of development of the events 

 are proportional to the temperatures which influence 

 them, divided by the accustomed yearly sum -tempera- 

 tures of the mother plants." This law is illustrated 

 as follows : ' ' Every separate seed contains the entire 

 relationship of the life -course of the mother plant to 

 the sum -temperatures of the place of its origin. Two 

 seeds of the same species, one taken from a mother 

 plant having passed its life -course in a yearly sum- 

 temperature of M degrees, the other from a mother 

 plant which has passed its life -course in a yearly sum- 

 temperature of N degrees, possess, therefore, a power 

 of development, or a sensitiveness towards acting equal 

 temperatures, which is inversely proportional to the 

 sums M and N degrees." If, for example, the sum- 

 temperature up to the time of blooming of Sambucus 

 nigra is 385 degrees, and the total sum -temperature of 

 the year is 5,200 degrees, then 385 divided by 5,200 

 equals .07 (approximately), which is the constant or 

 aliquote. 



It is not my purpose to enter into any discussion 

 as to the true physiological constant of climate and 

 plant epochs, but simply to state the nature of the 

 problem and to emphasize the importance of recording 

 climatological data along with plant data. It should 

 be said, also, that even a physiologically false constant 

 may serve all the purposes of an arbitrary standard 



*Carl Linsser, Die Periodischen Erscheinnngen des Pflanzenlebens In ihrem 

 Verniiltniss zn den Wiirmeerscheinungen. Mem. Acad. Sci. St. Petersb. ser. 

 vii. vol. xi. No. 7, p. 35 (1867). 



