8i 



Jeffrey, in his " Comparative Anatomy and Phylogeny of the Coniferales, 

 Part I, the Genus Sequoia" (" Mem. Boston Soc. Nat. Hist.," Vol. 5, No. 10, 1903), 

 illustrates some transverse sections of timber of this genus, where is shown a 

 substance which we think is similar to that occurring in the Australian Coniferse ; 

 its presence being plainly marked by the black spots occurring amongst the 

 tracheids, so that it at least is indicated in the wood of this genus. It is referred 

 to in the letterpress as a resin cell in contradistinction to other bodies or organs, 

 the resin ducts.* 



Jeffrey and Chrysler in a paper on Cretaceous Pityoxyla (" Bot. Gaz.," 42, 

 1-15, July, igo6), refer, under the name of " resin," to what is apparently the 

 same substance occurring in the rays of Pityoxylon Statenense, thus indicating 

 that it formed part of the wood substance of these trees of that geological period. 



Its presence is also well marked in Figures 40, 41, and 42 (in medullary rays) 

 of Dadoxylon ausfrale of the " Glossopteris Flora," by E. A. Newell Arber, British 

 Museum, and which show, in illustration, a marked resemblance to Callitris timber. 



As no resin or resin cells whatever could be found in the timber of Callitris, 

 by blazing or causing injury to the tree, or by chemical or any other tests, an 

 exhaustive investigation into the composition of this supposed resinous substance 

 was undertaken. 



That it was not resin was easily placed beyond doubt, for the alcohol used 

 in mounting and preparing the sections failed to dissolve it. 



That the dark portions filling these cells in all species of Callitris, and 

 similarly also those of Actinostrohts, Araucaria, Agathis, &c., is due to the presence 

 of a manganese compound, would, from the following results, appear to be reason- 

 ably proved. 



The chemical substances occurring in Callitris timber consist principally 

 of the sesquiterpene alcohol, Guaiol, which often crystallises out upon the surface 

 of the freshly cut timber ; the phenol, Callitrol (see articles on these substances 

 in this work), a sesquiterpene, and associated products ; but resins, as the term 

 is usually understood, appear to be quite absent, and the substance to which this 

 article refers was quite insoluble in all ordinary solvents for resins. 



The timber of Callitris species is often somewhat dark-coloured in the 

 centre portions of the log, although this darkening does not appear to be charac- 

 teristic of any particular species, and some specimens of the timber of identical 

 species are often less dark-coloured than are others. 



The ash of these darker portions always gave the most marked reactions for 

 manganese, both when fused with sodium carbonate and potassium nitrate, and 

 with Crum's method. 



*Solere(ier-(" Systematic Anat. of Dicotyledons") often mentions this brown substance when referring to the 

 researches of the various authors quoted by him. 



P 



