383 



From these results it may be assumed that manganese is an essential con- 

 stituent of these trees, and that their natural habitat is in those soils in which 

 an available form of manganese is present ; so that they should grow better and 

 become more robust in localities where this food material is available. It is 

 interesting to notice in this connection that most satisfactory results have recently 

 been obtained with manganese as a fertiliser, from which it appears that other 

 plants besides Rhus, Agathis, and Araucaria have need of sufficient manganese 

 to enable them to carry on their constructive functions in the most satis- 

 factory manner. (See article on the manganese compound in this work.) 



Reducing sugars were found in the oleo-resin of Agathis robusta, and their 

 amount determined. Reducing sugars were also detected in the latex of Araucaria 



Cunninghamii. 



Similar nitrogenous constituents were also shown to be common to both 

 trees. The volatile acids were also similar in both trees and were present in about 

 the same amount. 



The essential oil, removed from the oleo-resin of Agathis robusta by steam 

 distillation, consisted almost entirely of pinene, and this steam-distilled product 

 maybe considered to be an excellent commercial " oil of turpentine." It is also 

 present in some quantity (about 14 per cent.). Agathis robusta is thus a possible 

 turpentine-producing plant, and its commercial exploitation in this direction is 

 worthy of serious attention. From our present knowledge this is the only species 

 of pine growing naturally in Australia from which a product, agreeing in composition 

 with ordinary "oil of turpentine," can be distilled in commercial quantities ; and this 

 fact, together with the excellence of its timber, to say nothing of the value of its 

 resin, suggests the advisability of largely utilising this tree in forest cultivation, 

 because of its economic possibilities. The present policy of indiscriminate destruc- 

 tion of Australian vegetation, now going on all round us, is to be deplored, and we 

 raise our voices in protest ; while, on the other hand, we would indeed welcome 

 a vigorous policy in the opposite direction. Nature has been good to us in 

 Australia in providing such a natural vegetation suitable to the climatic and 

 other conditions of the country, of which we should not be slow to take advan- 

 tage for our own welfare and profit. 



The more saturated hydrocarbons, similar to those isolated from the latex 

 of Araucaria Cunninghamii, appear to be absent in the oleo-resin of Agathis 

 robusta, or, if any were present, it could only be so in very small amount. 



The principal constituent in the oleo-resin of Agathis robusta was resin, 

 and this was found to consist very largely of two resin acids, with about 10 per 

 cent, of neutral bodies, together with the remainder of the oil, &c. One of the 

 resin acids was readily obtained in a crystalline condition, and it melted at a high 

 temperature. The other, and more abundant acid, melted at a low temperature, 



