TERPENOIDS 239 



ents. The "primitive" {sejisii Baker and Smith) leaf venation pattern, 

 associated with cineole and pinine oils, exhibits the following featm-es: 



(1) Angle with midrib is less acute (approaching a right 

 angle). 



(2) Marginal vein is close to edge. 



(3) Reticulations between veins are prominent. 



The "advanced" leaf types, associated with phellandrene and 

 piperidine, possess the following attributes: 



(1) Angles of veins with midrib acute. 



(2) Marginal vein withdrawn from edge, a second marginal 

 vein withdrawn from edge, and a third marginal vein may 

 be in evidence (for example, E. dives). 



(3) Reticulations between major veins are reduced, and thus 

 more space for oil glands is present. 



(4) Looping arrangement of major veins particularly notice- 

 able in the bending of the marginal vein at positions of 

 major lateral veins. 



Elsewhere Baker and Smith stated: 



In other parts of this work we show that this alteration in leaf vena- 

 tion and chemical constituents is not local in its incidence, and that 

 the specific characters of each species are practically constant over the 

 whole range of its distribution, and numerous instances are given of 

 this constancy. 



That the constituents of the oil have been fixed and constant 

 for a long period of time must be evident by the fact that, to whatever 

 extent or range any particular species has reached, it contains the 

 same characteristic constituents, and has its botanical characters in 

 agreement. 



Baker and Smith prepared a phylogenetic tree designed to 

 show the evolutionary relationships of over 150 species of Eucalypts. 

 They also illustrated the general distribution of specific chemical 

 constituents of the oil. This distribution was purported to reflect the 

 major movement of the genus during its evolution in Austraha. 



The foregoing discussion may have given the impression that 

 only a few oil constituents had been detected. In fact, even in 1920 

 Baker and Smith listed forty oil constituents, and at the present time 

 it is almost a certainty that many more are known. Many of the com- 



