OBSERVATIONS ON CANADIAN CONIFER.E. 



29 



North American conifers examined, the largest resin-passages are uniformly to he met with 

 in the genus Pinus. Selecting those species of this genus exhihiting resin-passages of tlie 

 largest dimensions — those having a diameter of 0-30 mm. and upwards — we ohtain the 

 following : 



No. IL 



These figures again show that the dimensions of even the largest resin-passao-es fall far 

 below the requirements of the case, while for the majority of the resin-bearino- conifers the 

 average size falls lar below what is represented here, since for forty-five conifers of all 

 genera we find the average size of the resin-passages to be 0-131 mm., which is less than 

 half the average of the smallest coal filaments, and about two-thirds the size of the smallest 

 rods so far found. It is, therefore, evident that the coniferous trees of the Kootanie valley 

 do not oflfer any explanation of the origin of the Kootanie coals, at least so far as evidence 

 may be obtained from the structure of the Avood. 



On the basis of the data so far discussed, two hypotheses may be advanced as a means 

 of indicating the direction which future studies may profitably take. 



1st. The coniferous trees of the Kootanie period were capable of producing resin in very 

 large quantity, and in a manner similar to the production of kauri-resin by various species 

 ot Dammara. The resin remaining in the trees at the time of their decay, gradually hard- 

 ened, assumed the forms of the resin-passages in which it was produced, and the resulting 

 filaments or rods bore upon their surfaces the impressions of those structures. The liber- 

 ation of these rods, through decay or other causes, eventually led to their redistribution and 

 final aggregation through the action of water. 



Verification of this hypothesis necessitates a thorough study of the anatomy of the 

 genus Dammara, which we have not yet had an opportunity of doing. Through the kind- 

 ness of my friend Dr. G. L. Goodale, however, I have been enabled to examine the wood of 

 D. australis, one of the species constituting the principal source of kauri resin. I find 

 a total absence of resin-passages, so that the wood alone offers no solution of the question. 

 It is not to be overlooked, however, that even in those species where the wood contains no 

 resin-passages "these structures are present in the bark, and this part of the tree would 

 require careful examination before the question now under consideration could be given a 

 final answer. 



It should be also kept in mind that many ol the markings on these coal filaments are 

 clearly the impressions of scalariform ducts. As these structures do not occur in the 

 coniferje, it is clear that these plants do not satisfy all the conditions, and some other 

 explanation becomes necessary. 



