158 



ON THE CIRCULATION OF 



botany, in its nature a progressive science, has fully participated in that improvement 

 of all things, physical, political, and moral, which has distinguished the intermediate 

 years. And it is now discovered, what, indeed, was always too obvious, that 

 all the above-mentioned mutations in its nomenclature, have not only not added one 

 iota to our knowledge of the plant, either in structure or its relations to other plants, 

 but have led to error and confusion. For in the " natural system" most approved of 

 at present, this alga finds no place of rest among the Algae, and is said to be a sort of 

 mould, and figures away as an Azonium, a genus which stands next to, and 

 differs little from, the Linnaean genus Byssus ! — The preceding sketch may appear, 

 to the general reader, to be drawn up in the spirit of ridicule ; but I am sorry 

 to say that it is a true history, and only sins through defect, for at least one 

 other synonym (Dematium) might have been added to the useless catalogue. Herschel 

 has asserted, that, ** there is no science in which the evils resulting from a rage for 

 nomenclature have been felt to such an extent as in mineralogy," but he would have 

 divided the censure, had he bestowed a passing thought on the labours of cryptogamic 

 botanists."— Vol. II. p. 245. 



We conclude this brief notice, by putting- it to the good sense 

 of the author, whether the quaint and fanciful, though common, title of 

 " Flora" can possibly apply, in the most remote manner, to the half 

 of his very interesting work. 



ON THE CIRCULATION OF THE FLUIDS OF PLANTS. 



BY PROFESSOR DE CAN DOLLE, OF GENEVA. 



The ascending sap rises towards the foliaceous parts, charged essen- 

 tially, setting aside the earthy matter, with carbonic acid, or with 

 bodies capable of being converted into carbonic acid ; it loses by exha- 

 lation a very considerable quantity of the water which it contained, 

 and in consequence of the decomposition of carbonic acid gas it gives 

 off a large quantity of oxygen, and is reduced to simple carbon. 



This sap then exists in a proportion as to its elements very analogous 



gum — that is to say, of water and carbon. 



This gum, dissolved in the water of vegetation, must -run by the 

 intercellular passages, both in the bark and wood, when the causes 

 which determine the rapid ascent of the sap during the day cease to 

 operate ; this is what constitutes the descending sap. The sap which 

 runs down along the bark, not meeting with the ascending current, 

 passes without, obstruction to the root. 



The sap which runs down through the woody substances meets the 

 ascending sap, which, during the day at least, is carried up with force; 

 these two mixing with the water, which is exuded from the wood by 



