[KIRSCH] ORIGIN AND DEVELOPMENT OF RESIN CANALS 45 
especially created for them and which are subservient to the produc- 
tion of resin. Thus Mayr and Sanio speak of canal mother cells and 
initial canal cells, but both authors could find no rule govern- 
ing the appearance of these “initial” cells, and their divisions to form 
the canal, the exceptions being more frequent than any rule or rules 
that they could formulate. The reason for this is not-far to seek, 
and will be pointed out below. Schroeder (30, 21) writing of hori- 
zontal canals, says, that in the Coniferæ the medullary rays are 
always composed of more rows of cells when they are traversed 
by a resin passage than when they are not, but according to our view 
it will be seen that the multiseriate character of the ray is not due to 
the presence of the canal, but that the canal owes its existence to the 
presence of the multiseriate ray, and that whilst a multiseriate ray can 
exist without containing a canal, that a horizontal canal can never be 
present except in a multiseriate ray. 
Coming to the more recent authors, Coulter and Chamberlain’s 
Gymnosperms (4, 59) contains the following:—“These ducts are 
schizogenous in origin, a group of glandular cells being formed by 
repeated division, which separate by the splitting of common walls, 
and organize a passageway which they line, and into which they 
pour their characteristic secretion,’ showing that the resin producing 
character of the canal is regarded as of primary importance. Strasburger 
(33, 4) asserts that, “All the wood parenchyma of the Coniferæ is con- 
nècted with the formation of resin, and the starch contents of the rows 
of wood parenchyma cells is finally used up in the production of resin,” 
thus regarding not only the resin passages, but also all other 
parenchyma strands merely as resin-producing structures. So far is 
this idea prevalent, that the abnormal appearance of resin canals in 
the wood of certain Coniferæ as a result of wounding or disease, is taken 
to be simply due to the effort of the plant to produce a substance which 
will render the exposed part innocuous to bacteria and fungi, and to 
prevent the tissues from drying up. Thus Jeffrey (14) even goes as 
far as saying that the normal absence of resin canals in certain genera 
of the Conifer is an index of higher development, inasmuch as it 
constitutes an economical arrangement on the part of the plant in 
providing for the resin production only in case of necessity, and thus 
saving a large amount of material which might ordinarily be wasted. 
However, enough of this for the present, as this aspect of the question 
will be fully discussed later. For the present it will suffice to say that 
the results of the present research tend to establish a more primary 
function for the elements which constitute the resin canal, and to 
demonstrate that the resin canal itself is merely a portion of the inter- 
cellular system which traverses the medullary rays and which establishes . 
