31 



to his analysis 6*12 H-22 On, HZ 0, and identical in composition 

 with grape sugar: Berthelot by whom it was more fully investi- 

 gated also pronounced it to be identical with grape sugar and 

 very similar in its reactions : he regards it as a compound of grape 

 sugar with the isomeric substance eucalyn. Melitose is extracted 

 from the Manna by water, it crystallises in slender needles, 

 possessing a slightly saccharine taste. The other variety of 

 JNlanna is found upon the leaves of the E. dumosa (or Mallee 

 scrub) whose foliage is occasionally so whitened over with the 

 profusion of this substance as to present the appearance of being 

 'covered with frost : it is the secretion of the pupa of an insect of 

 the Psylla family ; and is called Lerp by the aborigines of the 

 Northern parts of the colony. It occurs in masses of aggregated 

 cones, covered with a filamentous material like wool, the color 

 varies from an opaque white to a dull yellow. These varieties 

 of Manna are of no medicinal value. 



Mr. S. J. LTMAN in moving a vote of thanks to Mr. Hoffmann 

 for the interesting and valuable paper with which he had favored 

 the College, said he expressed the sentiments of all present when he 

 stated that it had seldom been their lot to listen to a lecture con- 

 taining information of such interest. The information regarding 

 the Eucalypts is what he had not been able to find in books. 

 His attention was first called to these remarkable trees by having 

 observed one for the first time in the conservatory of a friend in 

 New Jersey, and he now held in his hand some of the leaves 

 plucked from the tree. On holding this leaf up to the light you 

 will at once perceive the essential oil vessels with which it is 

 filled, very similar to those of the Orange and Lemon peel. One 

 >of these leaves contains more essential oil than a whole plant of 

 Wintergreen, Lavender or Mint. When we consider the vast 

 height of the Eucalypts, the wide spreading branches with myriads 

 of leaves, capable of sheltering a small army, the question may 

 occur, what purpose in the economy of nature does this great 

 store of odorous oil serve. If, as Tyndal has proved, that the useful 

 office of the odors of plants and trees is to absorb the radient heat 

 from the earth and thus preserve uniformity of temperature by 

 which vegetation is preserved ; we can scarcely Conceive the influ- 

 ence these forests of colossal trees have upon the climate of Aus- 



