1922] RUDOLFS—SEEDS 219 
The maximum reaction change which the seeds were capable of 
bringing about in the small quantities of solution here used (100 cc.) 
was accomplished in a comparatively brief period of time, as is 
shown by the data in table II. Fifty corn seeds or fifty buckwheat 
seeds immersed in too cc. of magnesium sulphate solution, with 
osmotic concentration values of 7.0 atmospheres or less, produced 
the maximum reaction changes of which they were capable during 
an interval of one hour or less. The rate of reaction change of 
course is determined by the amount of solution used, total salt 
concentration, the number of immersed seeds, temperature, etc. 
After the maximum reaction changes which the seeds were 
capable of bringing about in the solutions had been attained, the 
P, values then remained approximately constant for an indefinite 
period. When the seeds were removed from the old solutions, 
rinsed with distilled water for a few seconds, and placed in fresh 
solutions with corresponding concentrations of the same salt, the 
phenomenon of reaction change again took place and continued 
until the maximum H-ion concentration was the same as that 
previously produced. The final P, values with corn in magnesium 
sulphate solutions were 3.9 to 4.2, except in the very dilute solutions, 
always varying slightly on account of differences in temperature 
and other environmental factors. ‘The seeds may thus be immersed 
several times successively in fresh solutions, the reaction changes 
taking place each time, but always bringing the final P, values to 
approximately the same point, which is fairly definite for each 
species in the solutions of a given salt, until finally the absorptive 
capacity of the seeds is exhausted, and equilibrium is established 
between seeds and solution. 
The exact cause or causes of the rapid reaction change of the 
solutions as indicated by changes in the P, values has not been 
determined with absolute certainty. There are without doubt 
several contributing factors, but all the experimental evidence thus 
far produced appears to indicate that the primary factor, and the 
only one which could account for the rapid reaction changes in the 
single salt solutions here used, is that directly related to ion absorp- 
tion by the seeds, the H-ion concentration increasing as the cations 
are removed from solution by absorption at a more rapid rate 
