76 THE ROYAL SOCIETY OF CANADA 
the girdling was remarkable for a thick tangential zone of resin canals 
which divided it completely into two. This zone of resin canals was 
so continuous that in splitting the wood fell apart at this point. Stras- 
burger (33, 529) explains this appearance on the assumption that the 
resin produced would serve to protect the wood, and eventually to turn 
the exposed part into heartwood (Verkernung der blosgelegten Holz- 
theile). That this is not the purpose is rather obvious, for there was 
an abundance of resin present in the tissues before the girdling took 
place. 
In his observations on the traumatic canals of Abies, Jeffrey (14 
7) states that, “The canals in question pour out a large amount of 
resinous secretion over the surface of the injured wood, and by their 
presence as a reaction to injury only afford a much more economical 
provision for antisepsis than the numerous resin canals which occur 
throughout the wood of Pinus.” This would be correct if, in the first 
place, the resin canals were normally formed in order to produce resin 
for antiseptic purposes, which has never been proven and has always 
been taken for granted. If, however, the ducts are secondary features, 
due not to any special need for them, but merely as the result of certain 
mechanical conditions in the presence of groups of parenchyma cells, 
the latter being of primary importance for the conduction of food- 
stuffs to the growing wood tracheids, it can then be understood why 
in some forms they occur only in the case of wounds or disease. The 
resin is simply an excretion, its presence being attendant on the pre- 
sence of the living cells. 
Again, if the phenomenon is one of reversion, why, in the majority 
of his observations, is reversion exhibited only in the case of the vertical 
resin passages and not in the case of the horizontal ones. Moreover, 
the vertical passages which are formed are mostly of the nature of cysts, 
thus showing that the phenomenon is very much localized even in the 
vertical direction. These features all point to an incipient formation 
of resin passages, rather than to a reversion to a former ancestry which 
exhibited a perfect, anastomosing system of canals. The reason for 
the absence of horizontal canals in these cases becomes clear when it 
is considered that the greatest growth in wounding is in the diameter 
of the affected part while the growth in height is normal or even reduced. 
At this point the case of a fossil Sequoia in which Jeffrey found 
both vertical and horizontal resin canals will prove of interest (12, 321). 
The canals in this form were of traumatic origin and Jeffrey states that 
the first few rings of growth formed after the wounding were “ unusually 
thick, as is ordinarily the case in traumatic wood” (12, 323). 
Now, if, according to Jeffrey, the resin canals in traumatic cases 
are reversions to an ancestry, which, by a large production of resin 
