INULINB. 87 



•tronger cohesion. M. Payen does not regard the hilum as a point 

 of permanent attachment, connecting the grain of starch to the in- 

 terior wall of the cell. He considers it as the orifice of the duct by 

 wiiich growth is effected by intersusception. In support of this 

 view, M. Payen observes, that in a great number of vegetable cells, 

 especially in those of the potato, and of the rhizomas, the globules 

 of starch are developed in such quantity, that it is actually impossi- 

 ble that each of these should be united directly to the inner wall of 

 the cell.* 



INULINE. 



This substance, discovered by Rose in the Inula helenium, pre- 

 sents certain analogies with starch. It forms the greater part of 

 the solid matter of the tubers of the Jerusalem Artichoke and 

 Dahlia, which do not contain starch. Inuline is dissolved in boiling 

 water ; on cooling it is deposited in globules, which, under the 

 microscope, appear diaphanous, adhering to one another like strings 

 of beads ; exposed to a temperature of 367° Fahr. it melts com- 

 pletely and acquires new properties, becoming soluble in cold water 

 and in alcohol. Inuline is transformed into dextrine and sugar by 

 the mineral acids ; but it possesses certain properties which show 

 it distinct from true starch. In the first place, it is not colored by 

 iodine ; and then acetic acid, which is without action on starch, 

 produces with inuline precisely the same effects as the sulphuric, 

 phosphoric, and hydrochloric acids ; finally, diastase, whose reaction 

 upon starch is so peculiar, so prompt, and so powerful, does not 

 cause any change in inuline. It is therefore easy to separate these 

 two substances when they are mingled, by treating the mixture 

 either with acetic acid, which dissolves the inuline, or with diastase, 

 which liquefies the starch. Inuline has been analyzed by M. Payen, 

 after having been dried at 253° Fahr. and having been melted at 

 367° Fahr. In both cases it has the same composition. 



Carbon 46.6 



Hydrogen 6.1 



Oxygen 493 



100.0 



The composition here is obviously the same as that of starch and 

 dextrine. 



OF WOODY MATTER AND CELLULAR TISSUE. 



The most solid part of plants, thai which forms in some sort theb 

 skeleton, is the wood in trees, the woody fibre in herbaceous plants. 

 Woody fibre, as it used to be prepared and considered, viz. by the 

 reaction of certain agents which have the property of dissolving the 

 gummy, resinous, and saline substances which are commonly asso- 

 ciated vi'ith it, consists, in fact, of two substances, one the cellular 

 substance, constituting the tissue of wood and of all the organs of 



 Payen, M6molres cit6s, p. 183. 



