282 



parenchymatous endodermal cells occur in about even j^roportions. The transpira- 

 tory surface occupies the mid-distance between the dorsal apices, there being no 

 decurrent channel in this species and, consequently, no \-entral surfaces so to 

 speak. Figure 194 has been cut near the bottom of the three oil cavities, which 

 can be seen on the outer edge of the whole median structure, and this is reproduced 

 in Figure iq6. Other structures can also be traced fron^ the remarks given under 

 pre\nous species. Figure IQ5 is a section through the middle of the oil cavities 

 of the leaves. Figure 196 is given to illustrate the sclerenchymatous cells enclosing 

 the bundles of the axis of the branchlet, and are well-defined objects in the plate. 

 At the top right-hand corner is focussed an isolated transfusion cell, the 

 other empty cells are of a parenchymatous nature. Figure 197 is a longitudinal 

 section of a branchlet and leaves, just cutting an oil cavit}' in the upper half of 

 the leaf. 



(c) Chemistry of the Leaf Oil. 



This material, which consisted of both forms of the leaves with terminal 

 branchlets, was collected at Coolongolook, New South Wales, 180 miles north of 

 Sydney, on the nth October, 1907. It contained many fruits, but all of them 

 were removed before distilling, so that the oil is that of the leaves only, together 

 with their accompan3'ing branchlets. This procedure was, however, found to be 

 unnecessary, because the fruits only contained traces of oil, and 331 lb. when steam 

 distilled for six hours did not give sufficient oil to enable it to be collected. The 

 yield of oil from the lea\-es was not large, and 290 lb. only gave 8 oz., equal to 

 0-172 per cent. 



The crude oil was but little coloured, and had somewhat of a turpentine 

 odour with but slight resemblance to that of the leaf oils of the Callitris generally ; 

 it was insoluble in 10 volumes of 90 per cent, alcohol. 



The oil of this species, although in most respects agreeing with those of the 

 Callitris leaf oils, yet contained a constituent in some quantity which has not been 

 detected in the oil of any other species of Callitris, although, perhaps, occurring 

 in traces in some of them. This constituent appears to be dextro-rotatory menthene 

 or some member of the menthene group, and when isolated by fractional distil- 

 lation, in as pure a condition as possible, it had a marked odour of menthene, 

 and altogether strongly resembled that substance. It was not possible, of course, 

 to separate it in a pure condition by distillation, nor was the amount of material 

 at our disposal sufficient for tin- purpose, hut iVom ilie results obta'ned tliere 

 appears Httle doubt but that a member of the €,„ H,s series does occur in liie leaf 

 oil of this species, as indications for an undetected terpene were not given. The 

 only Conifer from which we have succeeded in isolating hydrocarbons belonging 

 to the C,„H„ or C,„H.j„ series is Araucaria Cunninghami, and in this tree (;nly 

 from the latex of the plant. 



