3o8 



The walls of the mesophyll are iu)t plicate. All systeniatists of the genus 

 have described the leaves as incurved, and the reason is now ad\-anced for this 

 incurving to the presence of the stoniata on the inner (^upper") surface, which 

 occupy the two slightly conca\-e longitudinal portions of that jxirt, and the 

 protection of such from adverse climatic conditions — the two trans]:)iratory areas 

 being separated by the umbo of the dorsal surface o\'er the central \'ascular 

 bundle. The guard cells are exceedingly small, and only detected by a high-power 

 objecti\e. 



Both epidermal and hypodermal ceils, mostly in single rows except at the 

 edges, characterise the sub-cuticle substance where stomata do not occur, whilst 

 at the angle formed hv the dorsal and \cntral surfaces the h\'podermal cells are 

 found to be more numerousl}^ packed ^^Figures 22^ and 224), although a few 

 secondar\- isolated ones are occasionally found on the inner sides of the hypodermal 

 chain of cells ^Figures 223 and 224^, and much resembling these cells in structure 

 are found stone cells scattered throughout the mesophyll as shown in Figures 223, 

 224, and 225. Bertrand classifies similar bodies occurring in Araucaria Cunninghamii 

 as " fibres hypodermic." 



The meristele is elliptical, with an unbranched tibro-vascular bundle which 

 is surrounded with a fairly regular single or double row of parenchymatous 

 endodermal cells which, occasionally, encloses an oil cavity as in Figure 225 • 

 the\' include not only the bundle but also some transfusion tissue composed of 

 reticulate cells. 



The unbranched ^•ascular bundle has a normally orientated phloem which 

 generall}' has an oil cavity between it and the assimilating surface, probably to 

 serve as an auxiliary protection to the protoxylem. 



The oil vessels are not ducts or canals but cavities, as the various sections 

 show no continuity of channel, and these bodies occur, except in the above instance, 

 irregularly in the leaf substance, vide Figures 217-225, and are surrounded by 

 well defined yet thinner-walled stereome cells than those of the endodermis. 



Reticulated cells extending laterally from the central bundle compose the 

 transfusion tissue Figures 218, 2ig, 225 , which latter also has in its neighbourhood 

 a few sclerenchymatous cells in the lower left ])ortions of the section, and these 

 features can also be traced in nearly all th( other plates given of this species. 



(c) Chemistry of tiii: Lkaf Oil. 



This material, collected at Williamsford, Tasmania, was distilled on tlie 

 28th July, 1908. The leaves with terminal branchlets were used, and llie distil- 

 lations were continued for six hours, but the yield o{ oil was very small, and 

 538 lb. of terminal branchlets gave only 6| oz. of oil, e(|nal to ()-ny() jxr eenl. 



