IOWA ACADEMY OP SCIENCE 
51 
Clark^® in his paper concludes that the “Correlations between specific gravity 
of seed and vigor of the resulting seeding are less close than correlations be- 
tween the specific gravity of the seed and its germination; nevertheless such 
correlations do exist, it appears, in sufficient degree to make them of value in 
practice.” 
The specific gravity of the seeds before they were stratified was determined. 
First the dried seeds were weighed in a balance, then a common specific gravity 
bottle; weighed the bottle dry, full of water, and full of water and seeds to fill; 
the stopper to the bottle contained an opening clear through it. This method 
was used after consulting Prof. L. B. Spinney of the Department of Physics, who 
thought this would give best results: 
Density = ^ = 
Vol. = 
density 
Wt. = weight. 
(Wt. of bottle, seeds and H 2 O to fill) — (Wt. of bottle and seeds)=Wt. of HaO 
to fill. 
Wt. of H 2 O contained in bottle — Wt. of HaO to fill after seeds are put in 
.998 the desity of H 2 O 
No. of c. c. occupied by the seeds, i. e., the vol. of the seeds. 
. . density of the substance 
peci c gravi y (je^gity of H 2 O at same temperature. 
Two specific gravity bottles were used; in the first one the wt. of bottle full of 
H20==36.2467, wt. of bottle dry=29.5802, wt. of HgO contained=difference of 6.665 
gr. The first bottle was used for Iowa Blush, King and Jonathon apples, and all 
the rest were used in the second bottle. 
The wt. of second specific gravity bottle full of H20=45.527 
The wt. of second specific gravity bottle dry =20.626 
( 1 ) 
( 2 ) 
(3) 
The wt. of H 2 O contained 
24.901 
Wt. of bottle 
seed s and HaO Specific 
to fill Gravity 
Iowa Blush 
Kings 
Jonathan 36.20676 gr. 
Baldwin 45.413 
Willow Twig : 45.556 
Salome 45.556 
Winesap 45.500 
Greening 
Sweep Apple 45.512 
Crabapple 45.501 
Northern Spy 45.5625 
Seedling 
It will be noticed by the preceding table that there is a very wide range of 
variation in the different varieties. Using the Baldwin for example: 
(Wt. of HgO contained in bottle or 24.901 gr.) — (Wt. of H 2 O to after seeds are put 
998 
in, or 23.833 gr.) _ 1.068 _ 
~ .998 “ 
13. Clark, V. A. Seed Selection According to Specific Gravity. N. Y. Agri. Expt. Sta 
^3:335. 
36.24167 
gr. 
.935 
36.2211 
gr. 
1.188 
36.20676 
gr. 
.958 
45.413 
gr. 
1.072 
45.556 
gr. 
.449 
45.556 
gr. 
1.104 
45.500 
gr: 
.9031 
45.505 
gr. 
.665 
45.512 
gr. 
.893 
45.501 
gr. 
.2488 
45.5625 
gr. 
.867 
45.614 
gr. 
.620 
