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IOWA ACADEMY OF SCIENCE 
first year while others later. The same is true of the Black Locust, 
Kohinia Pseudo- Acacia and Cytisus Laburnum. In these seeds the dif- 
ferences are due to the unequal ability of taking up water required for 
germination. Delayed germination was also observed in Reseda lutea 
and Diantlius armerioA The seeds of Sonchus oleraceus are said not to 
germinate the following season but to do so at a later period. Wiesnek 
found in the ease of Viscum album, that the seeds would germinate only 
sparingly in the fall but readily in the following spring ; that these seeds 
have dormant periods of at least six months and that light is favorable 
for their germination. 
Gifford is authority for the statement in the case of the White Pine 
that a few seeds will germinate the first year, a large number the second 
and a few the third. It is well known that cones of the Jack Pine often 
hang on the tree for twelve or thirteen years — according to Sudworth** 
seven to nine years ; also that when a fire passes through, the cones burst 
open and the seed is ready to germinate. In many cases the seeds of 
forest trees will germinate better after being subjected to freezing, or 
in other cases endure freezing but germinate quite as well if not frozen. 
Many of the seeds of our common Eed Cedar will not germinate the 
first season. 
How long some seeds will retain their vitality has never been definitely 
determined for many species, although we have accurate data for many 
seeds, particularly the exhaustive work by DeCandolle.® It was found 
by this author that out of 368 seeds kept dry in air for fifteen years, 
only a small number — 17, were capable of germinating. Of these, five 
species of Malvaceae, 9 species of Leguminosae, and one Labiatae. The 
experiments of Beal“ are of interest in this connection. 
In 1879, Dr. Beal selected 50 freshly grown seeds of each of 23 dif- 
ferent kinds of plants. The seeds were well mixed with moderately 
moist sand; the mixture was then placed in a pint bottle, which was 
left uncorked, with the mouth slanting downward so that no water 
could collect about the seeds. The bottles were then buried three feet 
below the surface in a sandy knoll and at the end of 5, 10, 15, 20, and 
®Biol. der Planzen, 45. 
^Ueber die Ruheperiode undvon einige Keimungsbedigungen der Samen 
von Viscum album, Ber. Deutsch Bot. Gells. 15:505-515. 1897. See Kienitz. 
Bot. Centralb. 1:53. 
®Bull. Div. of Forestry, U. S. Dept, of Agr., 29:35. 
‘’Sur la Duree relative de la faculte de germer Ann. Sci. Nat. Ill, 6:373. 
1846. Physiologie vegetate 2:618. 
“Proc. Soc. Prom. Agrl. Sci. 26:89-1905. 
