344 TweENTy-FIFTH ANNIVERSARY REPORT. ~_ 
fruit. Those from medium sized white seed were fairly satisfac. 
‘tory, but the best results, as indicated above, came from the use 
of large white seeds. 
An effort was made to determine the causes for the differences — 
in specific gravities found in different seed of the same kind. The “a 
writer gives a list of the various chemical compounds found in 
the seeds with the specific gravity of each. This list is as follows: 
Specific 
: gravity. 
BAGS (a2 escent aieie oe ore ee eee 0.9I-0.96 
APOQUITIN 5 oh tye chee ee ee ee 1.285 
PCOCEH “2, ee ae bron ba Re Se ee te <1 3207. 
DEADENS oly casera 2 neh oe, A oe T53 
Cellos oo, rote vee Seat cle he ee ee ee Laas 
ASh about? 2 soo eh ae See ek Feo ee ee 2.50 
It will be seen from this list that fat is the only component which 
is lighter than water. It is evident that all those seeds which are 
lighter than water must owe this property either to containing a 
large amount of fat or else to the presence of imprisoned air. 
The writer says, “it is well known that seeds vary very greatly 
in their composition.” Wheat is reported as ranging from 8.58 
per ct. to 17.15 per ct. in proteids, 66.67 per ct. to 76.05 per ct. in 
carbohydrates, etc. ; 
These differences in composition may be due to differences in 
soil, climate, fertilization, or methods of culture. It is also stated 
that the specific gravity may depend on the ripeness of the seed. 
Wheat and rye have a lower specific gravity when dead ripe than 
when in the milk stage, while with peas the specific gravity in- 
creases with the approach of maturity. In many seeds with a rigid 
seed coat such as grape, squash, etc., the internal portion will, if 
for any reason it be not properly developed, shrink away from the 
outer hull forming an air space. In such cases a specific gravity. 
test would be a test of proper development. From what has been 
stated it may be seen that determining the specific gravity is by no 
means an infallible method of indicating the quality of seeds. It 
is of doubtful practical use and certainly only to be applied to cer- 
tain kinds of seeds. It may, however, be found of great service 
in removing impurities from seeds, whether these impurities be 
foreign matter or other kinds of seeds. 
a oe Wye re 
“oo Pale ee ee 
