1922] ATWOOD—FORMALDEHYDE 241 
other hand, if there is a gradual entry Stee eos 
of the salt into the seed, the curve 
will flatten out quickly, and after | S29ee23 
changing the seeds back into pure Hwata st 
water, the sudden and extensive rise e SSS 
we INnEO +00 
of the curve as the water enters will 
be followed by a subsequent sinking 
as the salt gradually diffuses out of 
the seed again. In this way, by long 
and careful soaking of seeds in water 
and solutions of higher osmotic con- 
ion, it is possi 2) $8885 S 
centration, it is possible to determine re aa 
‘ zi we 
whether the substance in solution is »| 3] ssoagges 
entering the seed coat. Frequent 4 aa Sw S 
oe : SU ab? Geo 
weighings are essential, each seed lot S| #§/S883R5 
being dried of surface moisture with PS Be Bebeerte a 
. . a * cal on) 
filter paper at each weighing. After palewhunk a Be 
*1° . 4 aomn to 
the curves approach equilibrium, the ee 2] gags os 
seeds in either solution are trans- EI eyes: 
ferred to the other one, with special & & 3 
attention to the behavior of the 
renee BA pei dome ait he 
‘ Slaacaa 
curves at this reversal of solutions. baby inated 
. . . * 4° An XHOoOnk yt 
The weighings were made in tripli- Slagdaags 
- + a a + om 
cate with 3.5 gm. samples. Seven- SSR OOM 
teen intervals, covering 292 hours of a Be ipa 
ro AaAMrH WH 
soaking, were followed by computa- 
tion of percentages. A study of the 
resultant curves (fig. 5) leads to the 
ol HH AHH oO 
conclusion that formaldehyde slowly 
penetrates the seed coat, and tha Es | 3 S339 
er . »" od ly Bie, Fas 
when the grain is again transferred | a ese Ge tedes 
to distilled water, the formaldehyde 
gradually diffuses outward. These 
results are shown in table I. The 
variations at the time of reversal are 
by no means so great, even with this 
high concentration of formaldehyde, tees 
ve as ae ae cae 
He baat aes cea cee 
PN ge age 
ete jeeet ees Moat “alee: 
Netty SNR hedonic anen 
CW dee Saal igh ea: 
ee, ie ae Ne 
DATA ON PENETRATION AS SUMMARIZED IN FIG. 5; PERCENTAGE WEIGHT INCREMENTS AT VARYING PERIODS OF SOAKING OF WHEAT 
* Figures printed in heavy type indicate soaking in formaldehyde; others in water. 
