768 SUMMARY OF CUREENT BESEAROHES RELATING TO 



internal cells of the pericycle remaining for a time in a merismatic 

 condition, and then becoming differentiated here and there into 

 laticiferous cells. 



The isolated resinous cells of the Tubuliflorae, which contain a 

 laticiferous and resiniferous secretion, occupy precisely the same 

 position, differing from them only in their form and in their mutual 

 relations. 



Chemical Constituents of Plants.* — M. Ballo is of opinion that 

 oxalic acid has a much more important function in vegetable physi- 

 ology than is generally supposed; the carbohydrates being formed 

 from the reduction of this and other vegetable acids rather than by 

 direct synthesis from carbonic acid and water. Tartaric acid, on the 

 other hand, is a product either of the oxidation of carbohydrates or 

 of the reduction of oxalic acid, as is also the glycolic acid which 

 occurs in unripe grapes and in the leaves of the wild vine. As regards 

 all other products of oxidation, the less the amount of oxidation, the 

 more complicated is the product and the more nearly related to the 

 original substance ; while, when oxidation is carried on further, we 

 get the original substances by which the plant is nourished. The 

 vegetable acids are the most common products of oxidation in the 

 plant. A portion of the oxalic acid is used in the decomposition of 

 calcium sulphate, the rest as the raw material for the production of 

 glycolic, tartaric, malic, succinic, and other acids. 



If formic acid is heated with nitric acid, it is oxidized into 

 carbonic acid and water, the nitric acid being reduced to nitrous 

 oxide ; but at the commencement of the process oxalic acid is formed ; 

 and the author believes that this process takes place in nature, 

 according to the equation : — 



2 H2 CO2 + O = Ha Ca O, + H2 ; 



and that this is one of the reasons why nitrates are so valuable to the 

 growing plant. In the living plant a portion of the nitrates is used 

 in the production of ammonia and other substances nearly related to 

 it, and another in the conversion of amide-compounds into alcohol- 

 compounds. The greater part is reduced to the state of nitrous oxide ; 

 and from this nitric acid is again formed through the agency of 

 oxygen and water. Hence a small quantity of nitrates can bring 

 about the formation of a large quantity of oxalates. 



Electric currents exist without doubt in the living plant, and it is 

 possible that in some cases these may be converted into chemical 

 work consisting in the decomposition not merely of water but also of 

 salts. The products of decomposition of these salts may cause the 

 formation of metal-derivatives at the negative pole, of derivatives with 

 negative radicals at the positive pole. Elsewhere these substances 

 may again combine with one another, and the same process be then 

 again repeated. Hence the comparatively small quantity of inorganic 

 salts found in plants. 



* Ber. Deutsch. Ohem. Gesell., xvii. (1884) p. 6. See Naturforscher, xvii. 

 (1884) p. 123. 



