42 
EXTRACTS FROM FOREIGN PERIODICALS. 
corolla. These two inverse curvatures are invariably observed. Thus it is 
undoubtedly the cellular tissue of each nerve, which, by its incurvation, effects 
the awakening of the corolla, and it is the fibrous tissue which, by its incurva¬ 
tion in an opposite direction, occasions the sleep of the corolla. 
I separated a nerve from the corolla of Mirabilis , still in bud and about to 
expand; I plunged it in water,, and it curved powerfully outwards , thus taking 
the curvature which effects expansion or awakening. I transferred it into a 
syrup of sugar: it curved in the opposite direction, or inwards. This proves 
that in the first case there was turgescence of the cellules, the external water 
being conveyed, by endosmose, towards the organic fluid which existed in the 
cellules, and that in the second case there was depletion of the cellules ; because 
their organic fluid, less dense than the external syrup, flowed towards the former. 
It might be concluded, since the expansion of the flower is owing to the turges¬ 
cence of the cellular tissue of its nerves, that its closing or its sleep was due to 
depletion of the same cellular tissue; but experience proves that such is not the 
cause of the sleep of the corolla.—QThe learned author of the paper then proceeds 
to offer his reasons for this statement, which, however, we must defer to a future 
occasion. We hope to extract further from the article in an early number.—- 
Ed. Nat. ]—Annales des Sciences Naturelles. 
4. On the Corolla of Cistaceee , by M. Edouard Spach. —The corolla (absent 
in some species) possesses only one whorl of petals, sometimes opposite to, some¬ 
times alternate with, the sepals, and always distinct. 
When the petals are five in flowers with five, four, or three sepals,* they 
never alternate with the sepals, as had been supposed till this time; but in 
neither case do they offer any regular or constant symmetry relative to the 
calyx.t 
When there are three petals,J they alternate with the three sepals of the 
inner whorl. 
In the order Cistaceee the petals, without exception very deciduous and inserted 
on the receptacle under the disk, are folded before the flowering, and turned in 
the opposite direction from the inner sepals. 
In the order Cechidacece the petals are in general more or less persistent, and 
even grow a little after flowering. They are neither twisted nor rumpled in 
aestivation, but simply imbricate, and are inserted at the base of a stiptiform 
receptale, or, occasionally, at the summit of this stipe. In some species of the 
* This formation is common to the majority of the species, and, with some other characters, it 
constitutes M. Spach’s Cistaceee. 
f M. S. has arrived at this conclusion by the examination of a large number of species. 
X The tripetalous and apetalous Cistaceee constitute our author’s Lechidacece : all have a pen- 
tasepalous calyx. 
