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. — £The 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.~\ — Annates des Sciences Naturelles. 



4. On the Corolla op Cistacece, 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 Cistacece 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 Lechidacece 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 Cistacece. « 



t M. S. has arrived at this conclusion by the examination of a large number of species. 



X The tripetalous and apetalous Cistacece constitute our author's Lechidacece : all have a pen- 

 tanepalous calyx. 



