336 



Mr. H. G. Smith, has made a chemical research in the matter " On the elastic 

 substance occurring on the shoots and young leaves of Eucalyptus corymbosa and some 

 species of Angophora." (Proc. Boy. Soc. N.S.W. : xli-i, 133, 1908.) The result of this 

 investigation showed this elastic substance to be identical in composition with 

 ordinary india-rubber, and that it is eventually oxidised to a white powder. A 

 vegetable wax was also isolated at the same time. 



If Eucalyptus caoutchouc could he obtained in quantity it seems reasonable to suppose that it 

 would have considerable commercial value. The small percentage amount, however, makes it at present 

 of scientific value only, without taking into consideration the difficulty of collection, its rapid change, and 

 that it only occurs at certain times of the year. 



Anatomy. 



This has been referred to to a very brief extent at Part I,- pp. 7, 8. There will 

 be a reference to Mr. W. B. Welch's papers on leaf-anatomy in Part LVII. 



Following is a very old anatomical reference : — 



These two genera (Eucalyptus and Acacia) still more uniformly agree in the similarity of the 

 opposite surfaces of their leaves. But this similarity is the indication of a more important fact — namely, 

 the existence equally on both surfaces of the leaf of those organs, for which, as I believe them to be in 

 general imperforated, I have adopted the name of cutaneous glands, but which by most authors are 

 denominated pores, or stomata of the epidermis. (R. Brown in Jcurn. Roij. Gcog. Soc, i, 21, 1832; in his 

 Coll. Works, i, 311.) 



The stomata in leaves as a rule are chiefly, or wholly, to be found on the 

 concave side, beneath which lies the soft green tissue with its ramifying air-passages. 



With reference to Mueller's notes in " Eucalyptographia," already referred to 

 at Part I, p. 8, of the present work, he has the following references to stomata in the 

 same work : — 



1. Lists of measurements of numbers on leaves of various species, under — ■ 



(a) E. pachyphylla. 



(b) E : phoenicea. 



(c) E. macrorrliyncha, 214 times mag. (Figure 1 of the Supplementary Plate)- 



(d) E. rostral a (Figure 1 of the Supplementary Plate). 



(e) Figure onE. Sieberiana plate. 



2. Drawings of cuticle (x 450) of 20 species, under E. microtheca (Supplementary 



Plate). 



E. Abergiana. E. marginata. 



E. alpina. E. microcorys . 



E. botryoides. E. microtheca. 



E. buprestiiim. E. peltata. 



E. clavigera. E. Raveretiana. 



E. Cloeziana. E. resinijera. 



E. globulus. E.setosa. 



E. gomphocephala. E. sideropMoia. 



E. incrassata. E. tetrodonta. 



E. largiftorens (bicolor). E. Torelliana. 



