NOTES AND MEMORANDA. 443 



limited supply of carbonic acid, hydrogen, or air, or in a vacuum and 

 in perfectly closed vessels. The gases developed exercise a strong 

 pressure, under which an incomplete decomposition of the carbo- 

 hydrates takes place, resulting in the formation of alcohol and acetic 

 acid, but without the assistance of any ferment. 



5. The same results ensue with fi-uits, flowers, and leaves, under 

 the ordinary pressure, with a limited supply of carbonic acid, hydro- 

 gen, or air ; but the decomposition is carried out so completely that, 

 when the disengagement of gas ceases, neither sugar nor starch 

 remains, but, in their place, abundance of alcohol and acetic acid. 



6. Fruits, flowers, and leaves placed, under the ordinary pressure, 

 in a limited supjily of air, carbonic acid, or hydrogen, do not remain 

 unchanged for any considerable time, but deteriorate, and the fruits in 

 particular become reduced to a brown and gelatinous mass. 



7. When the leaves, flowers, and fruits of certain plants disengage 

 hydrogen during fermentation, and under the conditions specified, 

 this gas probably arises from the decomposition of mannite, which is 

 a sugar with excess of hydrogen. In fact, fruits, flowers, and leaves 

 which contain mannite, when fermenting, disengage hydrogen in 

 addition to carbonic acid and nitrogen. 



8. When the receivers resist very strong pressure, and the sub- 

 stance: s are introduced in very small quantity, the sugar is almost 

 completely decomposed. 



Assimilation of Soda by Plants. — M. Deherain, continuing his 

 researches on the assimilation of mineral substances by plants, has 

 now turned his special attention to soda.* The following are the 

 chief results arrived at : — 



1. That sodium chloride may be absorbed by plants that do not 

 ordinarily contain any soda. 



2. That when the roots come into contact with a complex solu- 

 tion, this absorption takes place ouly when sodium chloride occurs in 

 considerable proportion in this solution, a condition not presented by 

 ordinary arable lands. Hence the occasional absence of sodium from 

 the ashes of terrestrial plants. 



3. That the absorption takes place much more readily when the 

 sodium chloride is presented only to the roots; but in this case it 

 ceases to be indifferent ; it is, on the contrary, utilized by the plant, 

 as may be demonstrated by the following considerations : — 



a. Haricots (on which the experiments were chiefly made) exhaust 

 their cotyledons when their roots are plunged in a solution containing 

 sodium chloride. 



h. Haricots plunged in a very dilute solution take up the salt in 

 much larger proportion than the water. The combination efiected 

 in this case between the salt and the tissues explains its more ready 

 absorption. 



These facts are readily explicable on the ordinary theory of difi'u- 

 sion (osmose). M. Deherain completely confirms the previous obser- 

 vations of Peligot as to the feebleness of the tendency of plants to 

 absorb soda. 



* 'Ann. dcs. Sci, Nat. (But.),' vi. (1878) 340. 



