[KIRSCH] ORIGIN AND DEVELOPMENT OF RESIN CANALS 73 
the thick mass of resinous tissue on the immediate border of the wound.”’ 
In the figure it can be seen that the canals are not in a position to pour out 
any resin directly to the wounded part, as they are really the cells 
furthest removed from it, the resin cells and not the resin canals border- 
ing directly on the wound. The quotation illustrates several points: 
1. It shows the general tendency to the formation of wood paren- 
chyma when there is an unusual amount of food available to the forma- 
tive tissues. 
2. The tangential band of resin ducts does not go completely around 
the annual ring for two reasons: 
a. In the immediate vicinity of the wound, on the left side, a large 
amount of parenchyma was formed, but as there was no tissue on one 
side of this, owing to the position of the wound, there were no tensions 
established sufficient to initiate schizogenous spaces. 
b. Where the ducts passed into a narrow zone of resin cells, on the 
right, not enough food went to this part to necessitate large amounts 
of parenchyma and hence no aggregations of cells occurred. 
The three parts of the ring in this root, exhibit the various forms 
which wood parenchyma elements can assume both in wounded and 
normal woods. 
In speaking of Sequoia sempervirens, Jeffrey states that, “The 
autumnal wood in this species forms a much thicker zone than in S. 
gigantea which is the cause of the greater weight and strength of the 
former species. “The canals are obviously situated in the autumnal wood 
and present a marked contrast to those of Sequoia gigantea . Says 
where they occur in the vernal portion of the annual ring.” This dif- 
ference in the position of the canals is to be expected, for large masses of 
wood parenchyma would be formed at the period or periods when the 
greatest growth would occur, and it can, therefore, be seen that the 
position of the ducts in these two species is in direct relation to the 
character of the wood of the two forms. 
In his conclusions, Jeffrey says, “The occurrence of resin canals 
in the reproductive axis of Sequoia gigantea is in all probability to be 
regarded as an ancestral feature.” “The presence of resin canals under 
certain quite definite conditions in the first annual ring of the branches 
of Sequoia gigantea, supplies a further argument for regarding the 
occurrence of resin ducts in the wood of this species as the retention of 
an ancestral feature, for it is only natural to find such a character 
appearing in the first zone of woody growth of the young branch.” 
However, the appearance of the canals, if at all of phylogenetic 
importance, can not be taken as a sign of reversion or retrogression to 
ancestral characters, but must rather be taken as a sign of progression. 
The canals, as has been shown, arise by the greater production of the 
