21 



IV. COMPARATIVE ANATOMY AND PHYTOGENY OF THE 



GENUS CALL/TR/S. 



A large amount of histological work has been done by European and American 

 botanists on the various groups and genera of Conifers, but the Australian genera 

 in general, and this genus in particular, have received least attention of all. This, 

 is probably due to the remoteness of this continent from the centre of old-world 

 scientific activity, and also the difficulty presented to them of obtaining material ; 

 consequently, any descriptions of the anatomy of these groups of Gymnosperms 

 will, no doubt, prove of interest, covering as they do quite new ground. 



The investigations in this direction were not undertaken so much from a 

 phylogenetic point of view, as to ascertain whether or not anatomical characters 

 would prove of assistance in systematic work, i.e., differentiation of species, for 

 in this work, as stated previously, the species are founded on even a broader basis 

 than that laid down in the previous published work, " Eucalypts and their 

 Essential Oils." 



The results will be found under each species, but they have not rendered 

 all the assistance anticipated from a taxonomic point of view, nevertheless they 

 have produced some novel features most interesting in themselves, for instance, 

 (i) the showing of a similar 

 disposition in some of the sto- 

 mata of the species to those 

 of Lepidodendroii Hickii, as 

 figured by Scott {" Studies in 

 Fossil Botany," Pt. I, p. i6o), 

 (2) the proving of the secre- 

 tory bodies to be cavities in 

 form, and not canals, as 

 obtains in exotic pines, (3) the 

 identification of a manganese 

 compound in the various 

 plant tissues, probably the 

 "resin" of former workers in 

 Conifers, as already stated, 

 and (4) the uniformity of the 

 ray cells. 



Lepidodendron Hickii Iransverse section of le.lf. ».*., vascular bundle 

 some of the large elements round it constitute the transtusion-tissue ; yi furrows 

 in which the stomata are placed, x bo. S. Coll. 51. {.G.T. C.) /\fK^ j^^gl"^ 



Lepidodendron Hickii. Epidermis;of leaf, with stomata. x ahout 300. 

 S. Coll. 51. (G. T. G.) 



Mil- ^CeTIr. 



The occurrence of this manganese compound or so-called " resin " in the 

 cells of the medullary rays of Callitris timber finds a parallel in the Cretaceous 

 Pityoxyla of North America, as illustrated by Jeffrey and Chrysler (" Bot. Gaz.," 

 42., 1-15 July, 1906). 



