V* 



sterilizer is supplied with a soft metal plug which melts off 

 and releases a spring, so breaking the circuit, when the water 

 is exhausted. Otherwise the rheostat would be burned out. 

 But now the heat prevents itself from being dangerous. A 

 general statement of these and other forms of regulation 

 might be valuable. It might indeed serve as a rule of thumb 

 for inventors. 



Bancroft 1 gives many excellent examples of regulatory 

 behavior as illustrating his "universal law." This law is 

 that "a system tends to change so as to minimize an external 

 disturbance." Some of the cases he notes are: 



The readjustment of prices through supply and demand. 



Tears caused by and discharging an irritating substance 

 from the eye. 



A splinter causing its own sloughing out. 



In chemistry, the occasional prevention of further re- 

 action by some reaction products. 



An insult causing a response which may prevent further 

 insult. 



The bending of trees to spill the wind. 



It is certainly tautologous to say that organisms behave 

 along lines of least resistance, for our only definition of least 

 resistance is the resistance that a system is first to overcome. 

 But any suspicion that the statement of Bancroft's law falls 

 short in a like way of being a synthetic judgment, is removed 

 after he has clarified it by illustration and comment. 



Adaptation of a group of animals or plants by selection 

 is a case of regulation if we regard the group as an organism. 

 The capacity for all the responses is not resident in all the 

 individual animals or plants, but is distributed among the 

 parts (individuals) of the entire organism (group). The 

 existence of the organism is maintained along with the life 

 of those parts which respond adaptively to the present con- 

 dition, notwithstanding the death of those parts which are 

 not adjusted so to respond. This is shown in the adaptation 

 of wheat to climate. A bushel of late ripening wheat will 



i Bancroft, W. D., "A Universal Law," Jour, Am. Chem. Soc., 

 XXXIII., No. 2, February, 1911. 



[TWO 



