11 



trochet* has appeared, which, together with phaenomena long 

 since known, contains also many new facts. Notwithstanding 

 all the numerous observations which have been published in 

 Germany respecting the structure of the Charce, M. Dutrochet 

 commences with a description of this remarkable genus of 

 plants, from which no one certainly would obtain a just notion 

 of it. Mention is made of a central and of a cortical system 

 of the Chara, which latter, in order to be able to observe the 

 circulation in the central system of C. flexilis^ must be taken 

 off. It is hence evident that M. Dutrochet has had before 

 him a Cham with compound cuticle, probably C. vulgaris, but 

 certainly not C. flexilis^ a case which also occurred to a cele- 

 brated philosophical botanist of Germany, who has written a 

 great deal respecting the circulation of sap in plants. 



The artificial removal of the outer cuticle in Ch. vulgaris 

 has long been known ; and if the plants be kept during win- 

 ter in a room, these membranes generally disunite of them- 

 selves and fall off in great pieces. M. Dutrochet also observed 

 that the course of the sap-current in the cells of the Char& is- 

 indicated by the position of the green globules, which are ar- 

 ranged in lines one after the other on the inner surface of the 

 cells ; and is at present of M. Aimer's opinion, that those 

 green globules are the seat of the motion which is observed 

 in the cells of these plants. M. Dutrochet has however seen, 

 (which is likewise not new) that there is a circulation of the 

 sap in such cells of the Charce as possess no green globules 

 on their inner surface ; and this is the case in all other plants 

 where hitherto these motions in the sap of the cells have 

 been observed ; therefore the source of the motion cannot be 

 sought for in those green globules. He has entirely over- 

 looked the fact that a similar circulation occurs in all the 

 cells of the so-called cortical layer of the Charce ; but it seems 

 as if, of all the innumerable memoirs which have appeared 

 on the Charge and the circulation of their sap, M. Dutrochet 

 had read no other than that of M. Amici. 



M. Dutrochet bound round the lower part of the cell of 



* Observation sur la Chara flexilis. Modification dans la circulation de 

 cette plante sous 1'influence d'un changement de temperature, d'une irrita- 

 tion m^canique, de 1' action des sels, des acides, et des alcalis, de celle des 

 narcoliques et de 1'alcool. Comptes Rendus, etc. Nos. 2. 3. 4. Dec. 1837. p. 

 77o. 



