196 



In a paper •' On the occurrence of Crystals in some Australian timbers," by 

 R. T. Baker (Journ. Roy. Soc. N.S.W., li, 435, 1917), the author goes into the general 

 question. The only Eucalypts referred to are E. hemiphloia F.v.M. var. albens (E. albens 

 Miq.), E. Dawsoni R. T. Baker, E. jnlularis Sm., E. polyanthemos Schauer, E. melliodora 

 A. Cunn., and E. paniculata Sm., but calcium oxalate was not found in all cases. There 

 are no figures referring to Eucalyptus timbers. 



The following general remarks referring to Oxalates amongst other waste 

 products will be found useful for reference :— 



Wastes not Useless. — In the course of the many and varied chemical changes which take place in 

 plants, there arise, especially in consequence of the destructive metabolism, a great number of compounds 

 which are not usable for the building of new parts, and are not again drawn into the metabolism. Some 

 of these are nevertheless of considerable service to the plant, and in varied ways ; as for example, in 

 protecting it from rrredatory animals by disagreeable tastes, or odours, in covering wounds by gummy or 

 resinous exudations, in attracting by colour or odour insects which effect pollination, &c. In spite of the 

 usefubiess of some of them, these substances are often called waste products, and this word may well be 

 ratained instead of the more technical term, aplastic products, which has been applied to them. For in 

 every household there are like products, properly " waste," as far as the direct economy is concerned, 

 some of which may nevertheless be collaterally serviceable. (Coulter, Barnes and Cowles, 1, 412.) 



A Warning Note in regard to Undue Reliance on Microscopic Structure 



for Diagnostic Purposes. 



" The role of the microscope in the identification and classification of the timbers 

 of commerce," by Irving W. Bailey (Journ. of Forestry, xv, 176, February, 1917), is a 

 valuable paper, and the following Summary and Conclusions at the end are supported 

 by evidence (Eucalyptus timbers are not used illustratively). 



1. There has been a marked tendency amongst those who have advocated the use of minute 

 anatomical characters in the classification and identification of wood, on the one hand, to over-estimate 

 the. possible economic applications of such diagnostic criteria, and, on the other hand, to greatly under- 

 estimate the variability of anatomical structures. 



2. The fact that the average lumberman (timber getter) and tradesman has to handle a large 

 amount of material in a comparatively limited space of time, eliminates the use of any except the most 

 obvious anatomical characters. 



3. There are, however, certain important, although somewhat restricted, economic fields of 

 usefulness for very accurate and reliable keys in the hands of technically-trained experts. 



4. The inaccuracies in existing systems of classifying woods are largely due to the fact that 

 investigators have not studied the limits of variability of anatomical characters, but have assumed that 

 their diagnostic criteria are constant and comparatively invariable. 



5. A careful study of some of the supposedly more reliable diagnostic criteria, such as the 

 distribution of wood-parenchyma, form and structure of the rays, type of pitting, &c, indicates very 

 clearly that these characters may fluctuate considerably, not only in certain families, genera and species, 

 but also in different parts of a single tree. 



6. There seems to be little doubt that avatomical characters must be largely dependent (depended) 

 upon in the construction of a thoroughly accurate and reliable key, such as is needed for general scientific 

 purposes and the use of technical experts in certain phases of commercial work. 



