106 BOTANICAL GAZETTE [FEBRUARY 
heat yield bears a fairly uniform relation to the age of the seed, 
this may be the cause, or it may merely be the reflection or symptom 
or result of that chain of causes, which finally deprives the seed of 
its germinating power. Even so, it is important to determine 
whether this is the case or not. And if it can be shown that the 
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| heat yield is proportional, or inversely proportional, to the age of 
| the seed, other things being equal, and a convenient method can 
be employed for determining this, we shall have, for the first time, 
a means of ascertaining the age and the viability of seeds. Those 
who have had any experience in buying seed have also known the 
