42 
BRITISH APHIDES. 
Boussingault remarked, also, that as the autumn 
approaches, the quantity of cane sugar in the samples 
experimented on increased more and more. He 
further found that the aqueous solution was ferment- 
able by yeast, and that during this process the whole 
of these sugars disappeared. 
'No mannite was found, but the composition of the 
secretion in August, he states, is identical with that of 
the manna of Sinai,’’ which substance Ehrenbiirg and 
Hemprich have discovered to proceed from the prick- 
ing of the leaves of Tamaris mannifera, by an insect 
known as Coccus manniparus. These authors describe 
this manna as falling upon the ground from the trees, 
and in such quantity that the Arabs eat it with their 
bread as if it were honey. 
The analysis, as given by the polarizer, by Boussin- 
gault is stated to be as follows : 
Cane sugar . . . 48’86 
Sucre inter verti . . 28*59 
Glucose . . . 22*55 
100*00 
He says he extracted as much as 26*7 grammes of 
these mixed sugars from one square metre of diseased 
lime leaves ; but only 4*4 grammes of the same from 
the leaves of the unaffected lime trees growing not far 
from the same spot. 
M. Boussingault calculates that a sick tree of “ le 
tilleul du Liebfrauenberg ” — for he considers the flow of 
this secretion to be a disease— may contain as much as 
from two to three kilogrammes of this manna. He 
points out that although it has the same composition 
as “ manna of Sinai,” it has quite a different origin. 
In the same year^' this notice was answered by 
M. Harting, who says, that observation permits him to 
affirm that this same substance is the excrement of 
* Harting, ‘ Comp. Rend.,’ tom. 74, p. 472. 
