in the Year 1835, ifi reference to the Physiology of Plants, 251 



cellular tissue, and endeavours to prove it from the nature 

 of this insoluble matter and from the manner of excretion 

 of these kinds of gums from the bark. According to the ex- 

 periments of Guerin * the elementary composition of this bas- 

 sorin is different from that of arabin (of the white soluble 

 gum), while cerasin, the gum of our Rosacece, is only di- 

 stinct from arabin by its difficult solubility, and by its being, 

 when long boiled with water, completely converted into ara- 

 bin, Bassorin consists of 10 m. g. carbon, 11 m. g. hydro- 

 gen, and 11 m. g. oxygen, while arabin is composed of 12 

 m. g. carbon, 10 m. g. hydrogen, and 10 m. g. oxygen. Ac- 

 cording to M. Guerin, starch has exactly the same compo- 

 sition as arabin ; he considers, however, starch to consist of 

 amidine and amidin tegume7itaire, and doe;^ not therefore call 

 both isomeric. Amidin tegumentaire has, according to Gue- 

 rin, the same elementary composition as the woody fibre, 

 namely, C7 H^q O4, which is not without influence on the views 

 of the structure of the granules of starch, and serves as a sup- 

 port to those who consider the starch granule as consisting of 

 a soluble interior and of a husk. 



We have seen that by treating starch with acids and dia- 

 stase it was first converted into gum, and then into sugar ; 

 have learned that gum and starch have the same composition ; 

 and are now informed by Liebig's experiments, that crystal- 

 lized cane sugar is isomeric with pure gum, or is equivalent to 

 it in its elementary composition. 



In physiology, the terms gum and mucus have the same 

 meaning, although chemistry distinguishes them. Those muci 

 which are stated by chemists to contain nitrogen merit a more 

 close examination. Thus M. Tromsdorff-f- lately found 7*5 

 per cent, of a mucus, soluble in water, containing nitrogen, in 

 the. fruit of Coriandimm sativum ; M. Pay en J, 0*1 per cent, 

 of a like substance in the tubers and stem of Oxalis crenata. 

 M. Herberger§ examined Sphcerococcits crispus, and found in 

 it 79 per cent, of a substance which he calls the gelatine of 

 algae, which according to our opinion, founded on the proper- 

 ties of the matter mentioned, does not differ from common 

 gum, being soluble in water and precipitated from the solution 

 by alcohol. The small proportion of nitrogen is not essential, 

 or is caused by some mixture. We consider the algae gelatine 

 of M. Herberger as cellular membrane, it being insoluble in 

 water and differing only from bassorin by the small quantity 

 of nitrogen it contains. 



* Ann. de Chim., vol. xlix. p. 248. f Archivfur die Pharm.f ii. 2, 



J Jfurn. de Chim. Med., Mai, 1835. 

 § Buchn. Repert.f vol. xlix. part 1, 2, 3. 



2K2 



