24 NOTES ON SpME TASMANIAN EUCALYPTS, 



the locality of the tree, for as long a period as possible. 

 Of each piece of timber a number of thin sectiojis should 

 be submitted to microscopic examination in addition, in 

 order that clues may be obtained for the interpretation of 

 the quantitative tests aforesaid. 



Quantitative tests are only valuable to the extent to 

 which they are supplemented by specific particulars which 

 will render the materials comparable. In old settled coun- 

 tries a considerable amount of information has been ac- 

 cumulated which enables an expert to say the directions 

 along which variation has proceeded. Scots Pine, for ex- 

 ample, is not a definite entity like refined gold, but a liv- 

 ing, plastic, variable something, and the results of the tim- 

 ber-tester must be variable, because he does not deal with 

 a constant. Although we have aggregations of individuals 

 which we label a species, it is pertinent to remind engineers 

 that no two blades of grass in the field, no two leaves of a 

 tree, no two trees, are absolutely identical. 



The same train of thought and action must be applied 

 to oil-results. 



I submit that it is unsafe to generalise in regard to the 

 composition of Tasmanian oils from the very few distilla- 

 tions that were available to Messrs. Baker and Smith. Very 

 many additional oils are required even for generalisations. 

 Before a complete research can be made, a full series of 

 oil-determinations in regard to a particular species should 

 include leaves taken every month of the year, and for as 

 many years as possible, as the meteoi-ological conditions of 

 any year differ from those of evei-y other year, in spite of 

 the search after cycles by meteorologists. Leaves should 

 be collected from the lower branches and from those at the 

 top, from those along the peripheiy, and from those at a 

 distance from it. Then we require leaves from trees of 

 various ages and sizes, from trees growing in as many dis- 

 tricts as possible, and in situations exhibiting as much 

 accommodation to environment as possible. The above 

 refer to spontaneous trees; the variation that takes place 

 in cultivated trees is almost a sealed book. 



Every charge of leaves submitted to distillation should 

 be backed by specimens in the herbarium, so that any ques- 

 tions that ]nay arise at any time in regard to anomalies, or 

 reputed anomalies connected with the oil results, may be 

 considered in connection with the coiTesponding botanical 

 material. The referential material in regard to oil-analysis 

 should be at least as complete as system at ists find neccssai-y 

 in their investigations of a species. As regai-ds every oil 

 referred to in literature, there should be a schedule of 



