AUSTRALIAN PTTTOSPORUM. 291 



this source. It will be observed that 1 do not impugn tlie 

 accuracy of those who state that a f^jum can be found in this 

 genus, for I am fully aware that a g'um, and a gum-resin or 

 a resin, may indubitably occur in the same genus, e.y., 

 Grevillea, Xanthorrhcea, Cedrela, Calophylla, Termmalia, &c. 

 The exudations I have been fortunate to obtain fall under 

 three species, P. hicolor, P. niidulaium,-dud P. rhombifoLium. 

 These substances do not freely exude, and I have not ob- 

 tained them in abundance, but in quantity quite sufficient to 

 enable me to state their characteristics and composition. 1 

 describe them in detail, 



Gum-Resins, 



Pittosporum hicolor. Hook: B, Fl. i. 113. 



Found in Tasmania, Victoria, and New South Wales. " Whitpwood," 

 " Cheesewood.'' 



The exudation from this species experimented on by me 

 was obtained from the Delegate District, near the Victorian- 

 New South Wales border, and has a most sickly smell, wliich 

 soon causes nausea and headache. It is of a greasy lustre, 

 of a dark orange colour, and is in irregular fragments for the 

 most part of the size of peas ; it looks like cracklings. It is 

 fairly tough when fresh. It causes paper to have a greasy 

 appearance when pressed upon it. It does not stick to the 

 teeth, but tastes like rancid fat. 



Very little of this substance appears to be found on trees 

 growing in what may be called "jungle" (" brush " is the 

 Colonial word), where they grow best, but on rocky ridges 

 and stony sides of mountains (t in uncongenial surroundings), 

 where they are rather stunted, it is much more plentiful. The 

 fruit is also coated with much resin, and trees on the ridges 

 are sometimes heavily laden with fruit. This is another 

 proof of what appears to be true as a general rule, viz., 

 that perfectly healthy, unwounded trees do not yield gum 

 or resin. It seems that this species yields a more plentiful 

 exudation than does P. undulatum. 



1, Examination of the Gum-Resin as collected. 



When the original exudation is treated with solvents, only 

 a portion goes into solution, the external portions of the 

 lumps being very insoluble, having hardened by di-ying, 

 owing to the evaporation of the essential oil contained in the 

 original gum-resin. 



