ig2o] SHULL— SEEDS 389 



It is my conviction, after a number of years of experience with 

 absorption phenomena, that absorption is a complex process 

 dependent on a number of factors, some of which may be external, 

 but many of which are internal. I have become convinced that 

 we should not expect a single formula or rate law to apply to 

 absorption in general. Each case of absorption is likely to present 

 a problem in itself, and to differ, slightly at least, from any other 

 case, because of both qualitative and quantitative differences in 

 the numerous factors determining absorption rates. 



Summary 



1. 



This paper deals with the quantitative influence of tempera- 



moisture 



sem 



Xanthium 



pennsyhanicum Wallr. and commercial and garden peas were used, 

 the latter with coats removed. 



2. The curves of water intake were found to be complex, but 

 can be represented by a logarithmic equation or series of equations 

 of the form y = a log IO (&r+i)+c. 



3. The analysis of the data presented does not support the 

 theory of Brown and Worley that the velocity of intake is an 

 exponential function of the temperature, but the velocity of intake 

 at any given moment in the seeds studied is approximately an 

 inverse exponential function of the amount of water previously 

 absorbed. 



4. The mean value of Q I0 in Xanthium seeds was in one instance 

 1 55, in another 1 .83, and in split peas of the Small Scotch Yellow 

 variety 1.6. 



5. These values do not indicate that absorption is conditioned 

 some single chemical change like simplification of water to 



hydrone as the temperature rises, but are believed to indicate 



absorpti 

 chemical 



main chemical changes with 



believed to occur in the colloids of the seed, and semipermeability, 



, __ 



the rate of water absorption. 



important factor in determining 



