"1 



to h'm analysis ('ij //_m (f\\, //j O, and identical in (•<»nn»o>itioii 

 with tjrapo sui:;ar : Hi'idiolot by wlioin it was nioro fully irivcsti- 

 jiatod also pronounced it to l»i^ idfiitical with i'rai)o su'j:ar and 

 very similar in its reactions : lie roirards it as a compound of <> rape 

 HW^nr with the isomeric substances eucalyn. >[(>litose isextructi'd 

 from the Manna hy water, it crystallises in slender needle.-., 

 ptjssessini;- a sliiilitly saccharine taste. The oth(>r varitity of 

 iNIanna is found upon the leaves of the U, (liininsn (or Malice 

 scrub) whose foliatre is occasionally so whitened over witli the 

 profusion of this substance as to present the appearance of beinir 

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

 the Psyilu family ; and is called Lerp by the uborii:ines of the 

 Northern ]);irts of the colony. It occurs in masses of airiire^ateil 

 cDues, covered with a lilanientons material like wool, the color 

 vari(!s from an opaipie wliite to a dull yellow. These varieties 

 '.)f 3Ianiia arj of no medicinal value. 



Mr. 8. J. fiV.MAN in moviti'j;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 wlieu ho 

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

 taining inform ition of such interest. The information regarding 

 the Eucalypts is what he had not bc'cn able to find in books. 

 His attention was first called to these remarkable trees l>v 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 leuf up to the light you 

 will at once perceive the es,5ential 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 

 AVintergreen, 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 vegct ition is preserved ; we can scarcely conceive the influ- 

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



