44 THE ROYAL SOCIETY OF CANADA 
1. The Resin Canals of the Conifere. 
The structures commonly designated as resin passages occur in both 
the woody and the cortical tissues of the Coniferæ (with the exception 
of Taxus) appearing in both regions in some forms, while in other cases 
they are normally limited to the cortical zone, and are then present in 
the tissues of the wood either sporadically, or under special, abnormal 
conditions only. 
Mayr (19, 53), in dealing with the secretory organs of Picea excelsa 
and Larix europæa, describes the canals as present in the hypodermal 
layers (in Larix only), in the primary cortex, in the secondary cortex, 
or soft bast, and in the wood. In our own treatment of these structures, 
however, only those passages present in the wood and in the phloem 
(and in exceptional cases in the pith) will be fully described and com- 
mented on, the ducts in the other regions of the stem and those in 
the needles being touched on in only a cursory manner. 
The substance called resin has been known for a long time, and is 
described by Theophrastus and Aristotle (19, 23) as the life sap of 
certain trees, their view being accepted by scientific men for many 
centuries and remaining in the popular mind until recently. From 
the time of Malpighi, however, it was generally recognized by men of 
science that the resin was a secretory product which originated in 
certain definite tissue elements and that from these structures it dif- 
fused into other parts of the tree. The nature of the organs which 
produced the resin and their mode of origin was still a controversial 
subject, two different views obtaining among the opposing factions. 
Karsten (16), Wigand (38), Theodor Hartig (11), and many others 
held the view that the resin passage was of lysigenetic origin, some of 
them asserting that the resin itself was a product of the disintegrating 
cell-membrane, whilst others (Hartig) held that the cells surrounding 
the cavity poured the resin into it. 
Frank (8), N. Miiller (23), and Sanio (29), on the contrary, cham- 
pioned the view that the canal arose schizogenetically, as an intercel- 
lular space, the secretion being due to the enclosing cells constituting 
the epithelium. The latter view has proven to be correct and has 
received confirmation from many sources, being accepted by all botan- 
ists of the present day. Furthermore, although Frank (7, 77) said that 
in old wood numerous canals may arise as a result of wounding, it is 
now known that the resin canals can only arise during the period of 
cambial activity, and that they are always more or less fully formed in 
the immediate vicinity of the cambial zone. 
The current view of the resin canals regards them as being struc- 
tures of a primary order, which are surrounded by cells which are 
