CAUSE OF DEATH. 213 
The death of this tree, and of many others, 
was brought about in the following manner. 
Many years ago in somewhat such a night as 
that of its death, the tree, then strong and solid, 
lost a great limb by the violence of the storm. 
Succeeding storms injured it in various ways, 
and thus tore open its tissues, exposing the un- 
protected stump to the destroying influence of 
air and moisture. Now, such is the powerful 
chemical influence of these two, apparently so 
innocuous and feeble agents, that it becomes 
impossible for wood to be long exposed to their 
attacks without rotting. The oxygen gas that 
forms part of the air, enters into union with the 
fibres of the wood, together with the moisture 
of the falling shower; and in process of time 
they render it quite soft, brown in colour, and 
very easily broken in texture. In the language 
intelligible to chemists it is converted into Humus ; 
that is into brown mould, much like that which 
forms part of our gardens. ‘This may be easily 
confirmed, if any of our readers will take the trou- 
ble to compare what they will find in the hollow 
trunk of some wayside tree with the mould of 
a flower-bed; only it is always to be remembered 
