336 REPORT OF THE HorTICULTURAL DEPARTMENT OF THE 
A quite definite correlation exists between the specific gravity 
of a seed and its germination. Seeds of low specific gravity do 
not germinate at all. Those in a range higher germinate scantily 
and in many cases produce comparatively weak plants. Seeds of 
highest specific gravity, or in the case of oil-bearing seeds, those 
of intermediate specific gravity, show the highest percentage of 
germination. 
In occasional species a correlation between the specific gravity 
of the seed and it's color has been observed. 
A few chance observations appear to indicate that there is a 
correlation between the specific gravity of the seed and its 
viability. It would appear that seeds of a specific gravity repre- 
senting the greatest storage of reserve material are longest lived, 
and that seeds of low specific gravity or of a specific gravity repre- 
senting a comparatively low storage or reserve material, soonest 
lose their vitality. 
To some extent a correlation appears to exist between the 
specific gravity of the seed and the vigor of the resulting plant. 
Results in this case are, however, not so clear cut as they are in 
the cases of the cultural correlations already mentioned. ~ * 
Differences in specific gravity are due either to differences in 
structure or differences in composition. If differences in com- 
position are not obscured by differences in structure, which they 
often are, the differing specific gravities to which they give rise 
are indexes to the quality of the seed. ; 
Differences in specific gravity may indicate differences in com- 
position due to different degrees of ripeness. In this case specific 
gravity is an index to ripeness. 
If differences in specific gravity are due to differences in struc- 
ture, these differences may or may not be correlated with some 
other cultural property of the seed, and accordingly specific grav- 
ity may or may not be an index to quality. 
It follows that specific gravity is by no means of unfailing 
reliability in determining the quality of seeds. 
INTRODUCTORY. 
The work herewith reported is an outgrowth of an investiga- 
tion conducted by Prof. S. A. Beach of this Station on seed 
selection as applied to the breeding of grapes. While weighing 
