240 



Cembra, P. filifolia, for in this instance the decunent leaves are more adnate to 

 each other and sometimes form as it were one complete triangular section of a 

 pyramidal leaf substance, similar to those quoted above. 



The central cylinder of the branchlet in this case occupies a small area of the 

 whole, and is surrounded by the irregularly disposed parenchymatous cells of the 

 mesophyll, and only traces of bundles are found in the lower portion of each 

 decurrent section near to the phloem of the midrib. The endodermal cells were 

 not found to extend around the outer surfaces of the oil ca^•itics. When the 

 section is taken clear of the oil ca\'ities, the spongy tissue of the mesophyll, 

 forms the bulk of the leaf substance. There is, also in this case, no ventral surface, 

 corresponding to that of the leaves of other species, for the transpiratory organs 

 occupy the three flat sides of the leaf-branchlet, the stomata thus not being 

 arranged all round as in Pi nits. The assimilatory surfaces are situated at the 

 dorsal ridges or angles of the leaf-branchlets, which is backed by epidermal, 

 hypodermal, and paUsade cells. 



The spongy tissue forms a good proportion of the leaf substance throughout. 



In other instances, the anatomy of the leaves taken from Tasmania, and 

 Glen Regis, Rylstone, when examined was practically identical. Both, however, 

 have a tendency to develop the dorsal surface at the expense of the ventral, and 

 in some instances in Tasmania no decurrent channel exists, as in Figs. 157-160, 

 where it is seen that there is no demarcation between the decurrent leaves, but which 

 form one whole, regular body around the central axis. In these four figures the 

 curved apices of the sectioned triangle correspond to the dorsal ridge of the leaf or 

 the assimilatory surface, whilst the surface joining these is transpiratory. Figures 

 157-159 show how irregularly arranged around the median bundles are the 

 parenchymatous cells and amongst which are a few transfusion tracheids. The 

 palisade parenchyma is poorly developed, whilst the spongy tissue is very much 

 so. Figure 160 has been cut through three oil cavities. Figures 161-2 are cross- 

 sections through the normal leaflets, and call for no special explanation except 

 that all the parenchymatous cells are empty. Figures 163-4 ^^^ longitudinal 

 sections cut through the nodes, and showing that tlie oil reservoirs are not canals. 



(c) Chemistry oi- the Leaf Oil. 



The results of the analyses of the oil of this loim of Callitris, found growing 

 in Tasmania, and also that of similar trees of the Rylstone district of New South 

 Wales, show them to be practically identical in composition, and it is evident 

 that the oils must have been distilled from the same species. The botanical 

 differences which had previously been supposed to exist between C. rhomboidea 

 of the eastern coast of New South \\'ales and the Tasmanian form are by this 



