250 



That there are limitations in regard to the interpretation of morphological 

 characters for the purposes of taxonomic research, I at once admit. Following is a 

 very good example of such searching after the light : — 



"As soon as three Orchidean forms (Monockanihus, Myanthus, and Calaselum) which had 

 previously been ranked as three distinct genera, were known to be sometimes produced on the same spike, 

 they were immediately included as a single species."* 



A hotanist often has to work on incomplete material, and to unduly disinter 

 the mistakes of morphologists, some of which (as regards Eucalyptus) have heen 

 made before the era of exhaustive field investigations on the genus inaugurated 

 by myself, would be as unnecessary as to point out the mistakes of scientific dis- 

 coverers in any other branch of science, who, by their work, have paved the way to 

 research on higher planes. 



Variation in oil. 



The variation in oil constituents within the same species has already been 

 referred to. To consider another aspect of the question, a man, when he makes a 

 distillation, which costs much trouble and expense (which is certainly the case with 

 Eucalyptus oil) is apt to stereotype its results; whereas, if he could make a hundred 

 times as many distillations he could take a broader view of the variability of the oils. 



Thousands of distillations require to be made before oil results can be based on 

 material as varied as that on which the systematists referred to as "morphologists" 

 base their conclusions. 



The distillations of Eucalyptus oils from material of authenticated botanical 

 origin, were inaugurated by me with the view {inter alia) of obtaining authentic 

 Eucalyptus oils for therapeutic and other jmrposes, and also of ascertaining to what 

 extent the oils could be used as aids in the diagnosis of species. 



Researches on Eucalyptus oils may, however, be employed for two ends : — 



1. Acquiescence in the naming of existing species {e.g., E. saligna and 



E. botryoides). 



2. Eor the naming of new species. 



As regards (1) if the premises be wrong, — if it should prove that E. saligna 

 and E. botryoides are identical species, what becomes of the statement that the oils 

 show them to be distinct ? 



If the answer be that there is some innate principle in these two trees that 

 morphology does not reveal, then we require very strong evidence that the alleged 

 oil differences are real and not apparent. But I have already touched upon this 

 point. 



It seems to me that an important difference between the morphological and 

 the oil-system determination is this : — 



In morphology you have a fixed standard termed the type. 



In oils you have no fixed standard, the oil-constituents being variable within 

 limits not yet determined and perhaps indeterminable. 



* Darwin's Origin of Species, p. 424. 



