636 Foreign and Miscellaneous Intelligence. 



some Cichoraceee. It is stated, that in these plants, the veins of the 

 foliaceous parts consist of what the author calls vital vessels, sur- 

 rounding the spiral vessels ; the duty of the latter is to absorb the 

 nutritive fluid, which they assimilate, and to conduct it into the vital 

 vessels, which form what is more properly called the system of circu- 

 lation. This is observed readily both in monocotyledons and dicoty- 

 ledons, by aid of the microscope. The progressive movement of the 

 nutritive fluid takes places in canals, which are more or less flexuose, 

 and which traverse the cellular tissue by the side of other vessels of the 

 same nature, in which the motion takes place in an opposite direction. 

 At intervals are anastomosing branches, which connect the two tor- 

 rents, and by which the liquid passes from one into the other, altering 

 its direction ; so that the whole constitutes a sort of vascular plexus, 

 the arrangement of which varies according to species. The obser- 

 vations of Professor Schultz have been confirmed by Messrs. Cassini 

 and Mirbel, who were appointed by the French Academy to examine 

 the facts. They state that the manner in which the subjects are pre- 

 pared by M. Schultz is very simple. In the Ficus carica he merely 

 cut away, with a sharp instrument, the cuticle, so as to lay bare 

 the vessels and the parenchyma, and then placed the preparation in 

 water under the microscope. But the most satisfactory illustration 

 of the phenomenon was found in the Chelidonium, an entire leaf of 

 which, when examined in water, by means of transmitted light in 

 bright sunshine, exhibited the movement beautifully, in its more deli- 

 cate and transparent veins. M. Schultz considers it very important, 

 that a flat, not a concave, mirror should be employed for this ex- 

 amination *. 



2. STRUCTURE OF LEAVES. 



An important memoir upon this subject has appeared from the pen 

 of M. Adolphe Brongniart. According to this observer, there is a 

 great difference between leaves that grow in water, and those that 

 grow in air. In the latter, there is a regularly formed cuticle on 

 both surfaces, which is perforated by openings of a peculiar nature, 

 which are what botanists call stomata. In the former, there is no 

 epidermis, and consequently no stomata. This difference of structure 

 is in direct relation with the respective functions of aerial and sub- 

 merged leaves, and with the respiration of plants. The functions of 

 leaves are to present the water, mucilage, sugar, &c. which is pumped 

 up from the earth through the roots, to the action of the atmospheric 

 air and light through the medium of extremely thin transparent 

 membranes. In leaves that grow in air, the cellules that contain 

 the fluids destined to be thus elaborated are inclosed within a cover- 

 ing called the cuticle, which protects the tender membranes from 

 coming too rapidly in contact with the atmosphere, and which, by 

 aid of the preparations, or stomata, above alluded to, retard evapora- 

 tion, and control respiration according to their number, size, &c. But 



* Aunales des Sciences. 



