Chap. IV.] 
MISCELLANEOUS. 
129 
or alburnum differ in different trees, and even 
parts of the rings of a tree may ripen sooner 
into heart-wood than other parts of the same 
rings, so that on the same transverse section of 
a tree there shall be more rings of sap-wood on 
one side than on the other. This may be ob¬ 
served in oaks; but on the scar of this tree no 
alburnum or sap-wood has been deposited for 
possibly nearly half a century. 
I published this account of this tree in 1844. 
In 1849, Dr. Lindley writes as follows: — 
“ Neither is it indispensable that bark should be 
present in order to allow the passage of sap 
downwards, as is proved by trees whose bark 
has been accidentally destroyed, continuing to 
live for many years. In such cases the supposi¬ 
tion is, that the falling sap passes laterally into 
the medullary plates, and descends by them 
until it gets into communication with those 
which end in bark, when the usual channel of 
descent is resumed.” 
I take this supposition to be the Doctor’s own 
particular supposition: and a supposition most 
difficult to swallow it is! 
But the Doctor makes it unnecessarily so. 
Why make the sap hop, skip, and jump from one 
medullary plate to another? These plates all 
K 
