To William Thiselton-Dyer   29 January 1884

29/1/84.¹

In revising the proof of the 10th decade of the Eucalyptography,² dear Mr Dyer, I have checked the citations of the remarks on the Euc. Manna from Chemical Journals &c. But some doubts have arisen in my mind, whether the “Sugar” of Eucalyptus described by Prof Jam. F. W. Johnston in the first vol. of the memoirs of the Chemical Society³ is what we call now “Mellitose”, i.e. the crumblike white exudation from Euc. viminalis. Prof. Johnston p. 159 remarks, that this Manna was in rounded tears and of slightly yellowish colour. Now, the real Mellitose is white and amorphous, and the question arises, could Professor Johnson⁴ have had the “Lerp”, to which Mr Dobson refers in the first vol. of the Royal Society of Tasmania.⁵ As the lerp is an organic fabric of a physllaceous insect, not the mere outflow after puncturing by Cicadae from Eucalyptus viminalis, the two sugars are neither physically nor chemically identical.

Sir Will. Hooker gave the Tasmanian material to Johnston [2]0⁶ years before he formed the Kew Museum; so perhaps no authentic specimens are extant any longer of the lot given to Mr Johnston; but I thought you might see or consult with Sir Joseph on the subject. As I have delt with the Melitose and the Lerp rather fully under E. viminalis in the 10th Decade, I should feel obliged, if you would not take the matter up in a litterary way before the Decade is issued.

Regardfully your

Ferd. von Mueller.

Perhaps Sir Joseph sent the Euc. sugar himself from Tasmania but he does not allude to the subject in the Flora Tasmaniae⁷

Eucalyptus viminalis