2 
KOYAL HORTICULTURAL SOCIETY. 
it formed, in fact, a sort of transparent and flexible varnish. Out 
of the sun the honey-dew still retained its viscous condition. 
On the 23rd, at seven in the evening, several leaves at the ex- 
tremity of a branch were washed and sponged, so as to remove all 
the saccharine matter. At six o'clock the following morning the 
leaves which had been washed seemed free from honey-dew, but, 
on examination with a lens, minute glistening dots, due to very 
small drops, were observable. At seven the same evening the 
appearance of the leaves remained the same. The day had been 
warm; the temperature in the shade 84^. 
On the 25th numerous spots of honey-dew were scattered over 
the leaves, but there were none upon the principal veins ; at three 
o'clock the temperature was 86°. 
During the night a violent shower removed a great part of the 
honey-dew formed during the evening. It became, therefore, 
impossible to follow, as had been proposed, the progress of the 
secretion upon the leaves washed upon the 22nd. A swarm of bees 
settled upon the tree. 
On the 27th the whole of the honey~dew had disappeared, in 
consequence of the rain which fell during the evening of the 26th. 
The temperature had stood at between 62° and 75^ ¥. On the 
morning of the 28th the leaves bore numerous spots of honey-dew, 
which had made their appearance during the night. On the 29th 
it had increased ; on some of the leaves it occupied a third of the 
surface. At two o'clock the temperature was 84^. On the 30th 
the honey-dew was very abundant. The Lime-tree remained 
covered with it till the commencement of persistent rains, which 
took place at the beginning of September. 
On two occasions, namely, July 22 and August 1, honey-dew 
was collected by washing the leaves. The solution, after treatment 
with lead subacetate to precipitate albuminous and mucilaginous 
matters, yielded a syrup in which crystals of sugar formed. On 
examination it contained a sugar analogous to cane-sugar, and also 
a reducing sugar. By fermentation with yeast the two sugars 
disappeared completely. In the fermented liquid, however, a 
substance remained possessed of very strong powers of right-handed 
rotation. This proved to be dextrine, already announced by 
Berthelot as existing in the mannas of Sinai and Kurdistan, and 
subsequently by Buignet in a manna occurring in ''tears" {manne 
en larmes). 
I have endeavoured to find mannite, and with especial care, 
because Langlois, an experienced observer, has found it in a 
