70 THE ROYAL SOCIETY OF CANADA 
of the stem and in the weaker shoots. According to our view, the 
occurrence of these structures in the cases mentioned by Jeffrey, would 
be explained by the conditions of growth being of such a nature as to 
necessitate an increase in the food-conducting or in the storage tissues 
of the vascular cylinder which is not required in the normal growth of 
these plants. Jeffrey, however, takes these appearances to signify a 
reversion to ancestral characters and since scattered wood parenchyma 
cells are normally present and even plentiful in all the species under 
discussion he takes the occurrence of these cells to denote a more highly 
specialized condition of the wood than where the resin ducts are normally 
present. 
Penhallow (25) dissents from this view, maintaining that the 
scattered condition of the cells is primitive, the aggregation into groups 
containing resin canals being of a higher order. He bases his interpreta- 
tion on various anatomical and phylogenetic considerations. Our 
results confirm the latter view, as a discussion of the main points on 
which Jeffrey bases his arguments will show that his observations can 
be much more logically explained and unified than by bringing in the 
question of reversion, which is, at its best, an element of very doubtful 
value, since it puts us further in the dark without possessing any redeem- 
ing features. 
The first point to be noted in connection with his data is that 
wherever the canals appear in the wood or phloem where they are 
normally absent, their presence is accompanied by an unusual vigor of 
growth. Thus, in the first case mentioned by Jeffrey (18, 442) where 
resin canals occur in the inner region of the first annual ring of certain 
shoots of Sequoia gigantea he states: “The material presenting these 
peculiarities in the first annual 1ing was taken from specimens accom- 
panied by unusually large cones ” “The resin passages Just 
described disappear in the upper part of the annual ring as it reaches 
what was originally the end of the yearly growth in length of the branch.”’ 
Further on he states that weaker lateral twigs of these branches generally 
showed no ducts. 
Now, in the cases where resin canals were present, the conditions 
were such as to render a large supply of food available to the growing 
tissues, for a large amount of foodstuff must be brought to those 
branches which bear female cones, especially just previous to and during 
the formation of these structures. These conditions would present 
themselves in any cone forming branch, but especially so when the cones 
forming on it are of unusual size. Normally, there is an abundance of 
scattered wood parenchyma Cells in these forms, and the advent of the 
unusually plentiful food supply would be fully sufficient to explain the 
aggregation of these cells in groups which would afford a place for schizo- 
