THE NATIONAL NURSERYMAN 
247 
tion, Carson, Wash., obtained a germination of 84% of western 
white pine and 73% of Douglas hr by extracting in dry air for 
ten hours, but only 48% and 24% respectively for these species 
by extracting for ten hours in saturated air under the same de¬ 
grees of heat. Tests are lacking for the other species, but we 
may reasonably assume that they are liable to injury in the 
same way, though not necessarily in the same degree. 
Methods of Testing Seed — 
Considerable attention should be devoted to the methods 
of testing in bringing out all that the seed is worth., This re¬ 
fers to sampling, medium of the tests, heat and moisture con¬ 
ditions, etc. It is true that the different species germinate best 
under a certain optimum combination of heat, moisture, ventil¬ 
Clearly, uniform results can follow 
only from standard methods, for in seed¬ 
testing the slightest differences in depth 
of cover, amount of moisture and heat 
produce wide variations. This has been 
proved again and again, both in the 
greenhouse and in the nursery and very 
clearly by two parallel samples of yel¬ 
low pine seed, one tested in a tray made 
of heavier wood than the other so that 
there was a greater moisture content 
and lower temperature. The actual dif¬ 
ference in sand temperature averaged 2o 
F., and the total germination in the 
heavier and colder box was 10% lower 
than in the other. 
Sterilization of the Seed —• 
Two other factors, disease and sterili¬ 
zation of the seed and the medium 
whether sand, soil, blotters, etc. may 
influence germination to a very marked 
degree. Sterilization to prevent damp¬ 
ing off is not so important in the green¬ 
house as in the nursery, provided there 
are right conditions for germination 
and proper care. Numerous tests have 
shown that with a very high green¬ 
house temperature and high moisture 
content an early germination, as well 
as great loss by disease, may result. 
Though this danger may be overcome 
by the use of sulphuric acid solution 
sprayed over the sand after sowing r 
there is danger of damaging the seed 
by the reagents. Experiments made 
by the writer proved that with 3/16 
ounce of sulphuric acid per gallon per 
square foot of surface applied to the 
greenhouse sand flats, and copious 
water applied twenty-four hours later 
to wash the acid away from the seed, 
lessened the germination for lodgepole 
pine and larch 22%, hemlock 97%, Doug¬ 
las fir 18%, western white pine 11%, 
western red cedar 100%. Spruce was the 
least injured, for one test gave 84% and 
the other 80%. Growth and development of the seedlings in 
the treated flats were noticeably much poorer and the roots 
curled and twisted. Sulphuric acid treatment of this strength 
and amount is most widely used in the nurseries and, though 
less injury would result in the nursery than in the greenhouse 
by washing the solution to a greater depth, there is neverthe¬ 
less danger of injuring the small and thin-coated seed by the 
direct contact with the acid solution. 
Sufficiently sterile sand may he obtained for the greenhouse 
tests from a pit eight to ten feet under the surface, provided 
the outer foot of sand is removed before it is taken out. In 
wick germinators the seed may be freed of spores by thorough 
rinsing each two or three days. It is well to take care not to 
press or shake the seed. 
TABLE I 
Total Germination and Rate of Germination 
ation and medium which is discovered only after considerable 
study. Even when these conditions are made apparent and es¬ 
tablished, it may not be feasible to conduct tests accordingly 
in one and the same greenhouse. A method must be sought 
which gives sufficiently satisfactory results for all species in 
one greenhouse and in one kind of medium. Methods of 
sampling and testing, as well as germination tests made in dif¬ 
ferent media, have previously been discussed. 5 
Pure seed gives more uniform results than the impure 
largely because errors in sampling are then less likely to oc¬ 
cur. Both for this reason and for convenience in handling and 
determination of the number per pound, sizes from different 
regions, etc., it is desirable to get very clean seed, even a com¬ 
plete removal of the hollow ones, for in this way standard meth¬ 
ods are more easily obtained. The Engelmann spruce listed in 
Table III was the most regular as well as the cleanest seed 
used in these tests. 
Species 
Pinus ponderosa 
Pinus contorta . 
Pseudotsuga tax. 
Larix 
Picea 
Thuja 
Tsuga 
Abies 
m 
a> 
Eh 
occidentalis 
engelmanni . 
plicata 
heterophylla 
grandis 
Pinus monticola 
Course of Germination 
Days 
|10|20|30|40| 501 601 
Percentage 
701 80|90|100|.5l O 
<D 
o> 
m 6 
<D 
r-H CD 
OCb 
is 
o 
o 
- 
0) 
a> 
m 
33 
6 
13 
32 
421 441 45 
72 
10000 
4-30 
S 
8 
27 
38 
461 511 
73 
114800 
4-34 
30 
9 
28 
43 
4 91 | 
85 
44000 
4-43 
14 
14 
29 
41 
431 471 
60 
131000 
2-46 
15 
33 
51 
55 
84 
240000 
2-3 2 
14 
8 
54 
57 
601 
71 
495000 
10-20 
8 
9 
25 
48 
611 6 51 
89 
465000 
-20 
6 
0 
3110 
11 12 
23 
19300 
Days 
20 
40 
60j80|100|140 
160 
200| | 
95 
27500| 
1751 0 | 2 | 61131 
Percentage 
2 41 4 21 4 91 5 41 
f< Larsen, J. A. Seed testing in Sand and in the Jacobsen Appara¬ 
tus, Journal of Forestry, Vol. XVI, p. 690, 1918. 
s Hartley, Carl. The Control of Damping-off of Coniferous Seed¬ 
lings. Bui. 453, U. S. Dept, of Agriculture. 1917. lA 
