VOLUME LXIX 



NUMBER s 



THE 





Botanical Gazette 



MAY 1920 



TEMPERATURE AND RATE OF MOISTURE INTAKE 



IN SEEDS 1 



Charles A. Shull 



(with pour figures) 



Introduction 



Some years ago Brown and Worley (i) published an account 

 of some experiments dealing with the influence of temperature on 

 the rate of moisture intake by seeds of barley. They found that 

 the value of Q I0 for the intake of water is high, approximating that 

 of the van't Hoff law. They interpreted this as indicating that the 

 rate of water absorption through a semipermeable membrane is 

 conditioned by some chemical change which occurs as the tempera- 

 ture rises. In discussing the probable nature of this change they 

 intimate that the water molecule is probably simplified as a result 

 of the temperature rise. In doing so they in a measure accept 

 Armstrong's hydrone theory of the structure of water. Cold 

 water, according to this conception, is composed of complex mole- 

 cules having at least several H 2 groups combined into a single 

 molecule. These more complex molecules are supposed to break 

 down into simpler groups as the temperature rises; the water 

 becomes less viscous, and is able to penetrate the semipermeable 

 coats of barley seeds more rapidly. The velocity of water intake 



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1 Contributions from the Botanical Laboratories of the University of Kentucky, 



no. 1. 



361 



