IS EUCALYPTUS VARIABLE ? 327 



Some years ago, when Superintendent of Technical 

 Education, I determined to ascertain whether this qualita- 

 tive test of Eucalyptus odour was capable of leading up to 

 further results. Accordingly I obtained samples of com- 

 mercial Eucalyptus oils and also watched their distillation 

 in the country, but found, as a general rule, that the various 

 kinds of leaves were not rigidly kept apart. I therefore 

 resolved, with the advice of Dr. T. L. Bancroft of Brisbane 

 and the active co-operation of Mr. Owen Blacket, c.e., 

 Lecturer in Engineering at the Technical College, to erect 

 a model still capable of holding large charges of leaves, 

 and to distil only those leaves obtained by my own collector 

 or through agencies which permitted the origin of the leaves 

 to be precisely checked from a botanical point of view. In 

 this way, and in this way only, could Eucalyptus oils of 

 many species, absolutely true to name, be obtained for 

 research. My transfer to the Botanical Gardens removed 

 me from this domain of botanical technology and the work, 

 thus initiated has been continued and extended by my late 

 assistants Messrs. Baker and Smith. 



(f) Stomata — Mueller, in Eucalyptographia under E. 

 pachyphylla and E. phoenicea, has classified some of the 

 Eucalypts according to the number and distribution of the 

 stomata. He styles the leaves, — 



1. Hypogenous according to the presence of stomata on 

 the under surface only. 



2. Heterogenous according to their presence on both 

 surfaces, but less numerous above than below. 



3. Isogenous, when they are present on both surfaces, 

 but approximately equal in number above and below. 

 "This almost equal distillation of the stomata coincides 

 with the similarity of the colour of both sides of the leaves." 



Examination of the stomata cannot, however, be used 

 for diagnostic purposes with any degree of certainty, 

 because of the variation in the distribution of the stomata 

 even in the same tree. 



