335 



obtained by collecting the material which had accumulated upon the stumps ol 

 trees felled some time previously. [Masses of gum-resin were found upon these 

 stumps, mostly at the junction of the inner and outer bark. The material was quite 

 Huid beneath the crust which had earh' formed upon the surface, and it was evident 

 that the liquid material beneath this crust had been forced up from below by root 

 pressure, the film of partly hardened resin protecting the material forced up later, 

 and so retarded, if not prevented, the evaporation of its volatile constituents. 

 That this is so appears evident from the large masses which had accum.ulated 

 upon the stumps of the trees, and by the presence of the ^•o]atile constituents found 

 in this exudation. Corresponding results were also obtained under our own 

 observation with the exudation of a large tree of A. Bidwilli groNxing near Svdnev 

 (see under that species). 



This fact is also interesting as suggesting the possible formation, or com- 

 pletion, of some of the constituents of the plant in the root portion of the tree, and 

 not in the leaves, because the upper portion of the tree ha^^ng been removed, 

 the " laboratory " must have been below the ground, as the only place from which 

 the material could have been derived. Had it not accumulated in this wav it is 

 certain that the verv volatile hvdrocarbon found in the latex would not have 

 been discovered. The occurrence in this tree of natural hydrocarbons belonging 

 to the Cj„H.,j, series, and probabh' also to the Cj„Hj^ series, is particularly 

 interesting, and may, perhaps, assist somewhat towards the elucidation of some 

 of the problems concerning the natural formation of the terpenes and of the resins. 



Heusler ^" Chemistry of the Terpenes," p. i8' suggests that hexahvdrocymene 

 does not occur in nature ; and Gildemeister and Hoffman ("Ethereal Oils," p. 182) 

 that the hydrocarbons of the formulse C.^H,^, and Cj„H.,,., are not known with 

 certainty in ethereal oils. If the formation of the saturated h}'drocarbon is com- 

 pleted in the root portion of the tree, as from the results of this investigation 

 appears to be the case, then it is hardly to be expected that the saturated hydro- 

 carbons \xi\\ be found in ethereal oils as usually obtained from the leaf portion of 

 the plant, because alteration rapidly takes place under the active influences of the 

 growing tree, with the ultimate formation of unsaturated hydrocarbons, terpenes, 

 and resins. 



The trend of the reactions which take place in the plant during the formation 

 of these complex substances is not known with an}- degree of certainty, although 

 evidently produced from simpler compounds. Baeyer (Ber. d. Chem. Gesell. 3, 66, 

 1870) offered an explanation for the formation of Butlerow's methylenitane, by 

 the simple combination of six molecules of formaldeh\-de. By similar reasoning 

 a suggestion might be advanced for the formation of members of the Cj„H.,^, 

 group of hydrocarbons, from which the terpenes and resins would ultimately 

 be deri^'ed. The menthane molecule can be arranged from ten molecules of formal- 

 dehyde, all the oxygen atoms being (eliminated. 



