VEGETABLE ACIDS. 131 



Peetinc. Pectie aeia. 



Carbon 42.9 42.8 



Hydrogen 5.1 5.2 



Oxygen • 52.0 52.0 



100.0 100.0 



I have thought it right to speak at some length of these two prin- 

 ciples, as they appear to play an important part in the phenomena of 

 vegetable life. A careful study of pectine and pectic acid will very 

 probably aid in throwing light upon the metamorphoses which organic 

 substances undergo in the act of vegetation, Pectic acid has been 

 found in every plant in which it has been sought for ; M. Braconnot 

 discovered it in the turnip, carrot, beet, peony, in all bulbs, in the 

 stalks and leaves of herbaceous plants, in the wood and bark of all the 

 trees examined, in all kinds of fruit, apples, pears, plums, cucumbers, 

 &c. M. Braconnot is even very much inclined to think that pectic 

 acid may constitute the essential principle in the cambium or organ-^ 

 izable matter of Grew and Duhamel.* 



OF VEGETABLE ACIDS. 



In the series of bodies which we have now considered, one only, 

 sugar, possesses the property of crystallizing. All the others are 

 amorphous, and their globular disposition and gelatinous qualities 

 have led to the presumption that they form in some sort the line of 

 demarcation between things without and things endowed with life. 

 It was also imagined that these amorphous matters, that these pro- 

 ducts of the vegetable organization, almost organized themselves, 

 would alone suffice for the nourishment of animals. This idea, 

 however, is not well founded ; for if it be true that albumen, caseine, 

 legumine, starch, and gum, are powerful elements of nutrition, it is 

 equally so that sugar may perform an important part in this process, 

 by acting in the same manner as starch, the oils, and other principles 

 of ternary composition, in becoming like them a useful, often an in- 

 dispensable auxiliary of azotized alimentary matters. 



This disposition to consider the amorphous state of the more im- 

 portant immediate principles of vegetables as a special and distinctive 

 character, cannot be maintained beside the recent observations of 

 Mitscherlich. This illustrious chemist has found, that if the mineral 

 precipitates which are deposited in liquids, are in many cases form- 

 ed of crystals more or less regular, they are also sometimes compos- 

 ed of small spheres or aggregated masses, the particles of which do 

 not unite in a regular way as crystals, but remain separated by a 

 thin layer of fluid. Examined under the microscope these masses 

 present themselves under the form of flocks and of shreds, having a 

 granular or gelatinous appearance, and which remain soft and flexi- 

 ble like fresh vegetable or animal substances, so long as they are 

 kept under water ; it is only in drying that they become pulverulent 

 or acquire the vitreous aspect. f 



* Braconnot, op. cit. vol. xxviii. p. 171. 

 1 Berzelius, Ann. Report, 1841, p. 20. 



