32 
IOWA ACADEMY OP SCIENCE 
maple. The seeds fall on the damp earth or mud and here the condi- 
tions are favorable for immediate germination. 
The seeds of the ash and horn-bean begin to germinate the year after 
they ripen; it is also known that the seeds of many trees and some 
shrubs which mature early in the season do not retain their vitality for 
germination a great length of time. The following experiment was con- 
ducted A\dth the common soft maple {Acer saccharimmi) . 
On June 3d the samaras of the species were beginning to fall from 
the trees. They Avere collected and kept under different conditions as 
follows : A large number of seeds were stored in the cooling room of 
the college creamery at 45 degrees F. ; another sample Avas left in the 
laboratory exposed to dry atmosphere; still another sample was left in 
a pasteboard box between folds of damp cloth; another was placed in 
damp sand immediately after being picked from the ground. 
