33 



so that the idea suggests itself that the formation of the characteristic resin known 

 as sandarac is primarily due to the alteration in some way, perhaps by oxidation 

 or condensation, of these hydrocarbons in association with the terpenes. 



Apparently the origin of the sandarac resins is different from that of the 

 ordinary Pinus resins, and in both Finns and Callitris the oils of some species 

 consist largely of pinene, and yet the resins are not similar. 



From chemical evidence C. Madeayana and Araucaria Cunninghamii are 

 somewhat closely related, and this is also supported botanically. 



It has been determined that all constituents occurring in the oils of the 

 Callitris reach a maximum in that of one species, although perhaps present only in 

 traces in some of the others. It is assumed, therefore, that a hydrocarbon of the 

 CjnH,j^ series may occur at some time in the oils of the Callitris generally. The 

 difficulty of detecting this, when only occurring in small amount in association 

 with pinene and similar terpenes is apparent, and it was thus fortunate that 

 C. Madeayana supplied evidence in this direction. 



The leaf oils of the Callitris all contain, either in large or small amounts, 

 pinene (both modifications), limonene (both forms), dextro-rotatory borneol and 

 its acetic acid ester (perhaps with the exception of C. Tasmanica), and geraniol 

 and its acetic acid ester. The ester of terpineol, the acid of which is probably 

 butyric, is present in some species, if not occurring in traces in all of them. 

 Although the constituents in all the oils appear to be the same, they vary in amount 

 in each well-defined species, thus corresponding to the morphological differences 

 of the plants themselves, and in this respect are comparatively constant, so much 

 so, that each species has its own characteristic oil, and the determination of the 

 amount of its chemical constituents is sufficient to indicate its origin in most 

 cases. We have gone to considerable trouble in the endeavour to decide this point, 

 and the results herewith published show distinctly that the influences which were 

 instrumental in bringing about distinctive characteristics for each species, also 

 acted directly upon the character of the oil constituents in a corresponding 

 degree. 



Whether the predominant constituent in the oil of the original ancestor 

 of the genus, was the terpene pinene, or limonene, it is not now possible to decide, 

 but it is apparent that changes have been active with the several members of 

 the genus Callitris. The time necessary for the accomplishment of this altera- 

 tion, through varieties to distinct species, must have been of an extended nature, 

 and, consequently, for this and other reasons, we assume that the Callitris of 

 Australia is an ancient genus. 



In two instances evidences have been found indicating a close botanical 

 and chemical connection between Callitris somewhat closely related, and showing, 

 as it were, a branching off from a species. These were, firstly C. rhomboidea of 



