242 BOTANICAL GAZETTE [NOVEMBER 
as the writer (7) in earlier work has found to maintain with other 
grains in the presence of gram molecular solutions of sodium 
chloride. From the consistent behavior of these curves we must 
conclude that formaldehyde penetrates the coat of wheat, although 
such entry is slow. The work of BAKKE and PLAGGE (10) offers 
interesting confirmation of these conclusions. In their work the 
rate of entry of water and of 1-320 formaldehyde was compared. 
After a dip of fifteen minutes they found the weight increase about 
the same for the two, and concluded that water entry from 1-320 
is not greatly different from the absorption of distilled water. The 
question of the comparative entry of water and of formalde- 
hyde solutions becomes specially interesting in the light of 
Cottis’ (18) work with barley, which indicated that the entry of 
solutions, and hence the seat of selectivity, is in the germ end of 
the grain. 
DIASTASE 
In order to determine the effect on starch digestion of the 
presence of formaldehyde, a series of twenty-six test-tubes was 
filled each with 10 cc. of 25 per cent soluble potato starch solution. 
To all but two of the tubes 1 cc. of a filtered solution of Merck’s 
medicinal diastase of o.5 per cent concentration was added. To the 
test-tubes was then added 4 cc. of a formaldehyde solution varying 
in concentration from 1-1000 through 1-400, 1-320, 1-240, 1-160, 
1-80, I-40, I-20, I-10, 1-1, and pure 40 per cent commercial formal- 
dehyde solution. Each condition was run in duplicate. These test- 
tubes were then incubated for 1.25 hours at 40°C. It was presumed 
at the beginning of these tests that it would be essential to determine 
the percentage of reducing sugars as a measure of the degree of 
digestion. It was found, however, that by modifying the methods 
used by APPLEMAN (3) and SHERMAN (48), it was easily possible 
to detect comparative differences in the amount of digestion by 
the deepness of coloration of the solution upon the addition of 
iodine. The stock solution of iodine as used eventually by dilution 
ro cc. to 100 cc. of water was prepared with 1 gm. iodine, 5 gm. 
potassium iodide, and so cc. water. In the series enumerated the 
gradation of color was so obvious, from the deep blue of the check 
to the clear solutions where digestion was complete, that the 
