1922] ATWOOD—FORM ALDEHYDE 239 
sion. Brown (15) showed this to be conspicuously the case for 
barley, while SHutL (49) found semipermeability of seed coats a 
rather general situation. SCHROEDER (47) showed that the coat 
of wheat is permeable to the entry of mercuric chloride, iodine, 
alcohol, ether, chloroform, and acetic acid when in water solutions. 
Injury to the seed coat destroys this seed coat power of exclusion. 
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CONCENTRATION 
Fic. 4.—Effect of varied concentrations of formaldehyde on percentage germina- 
tion, Turkey Red wheat from Moro, Oregon: solid line shows percentage for seeds 
germinated in blotters, broken lines for seeds in soil indoors and outside; ten minutes 
of soaking; summary of 3000 seeds tested. 
Miss Hurp (34) found that injuries from the entry of fungicides 
are much worse when seed coat cracks exist over the embryo. 
Two methods were employed in studying the relation of the 
seed coat of wheat to formaldehyde entry. After various diffi- 
culties in technique, at the suggestion of Dr. E. M. Harvey, the 
method was finally adopted of sealing the seeds one at a time to 
the end of small glass tubing, into which formaldehyde solution was 
placed. After allowing the seed to be in contact with the solution 
