941 



On the Gelatinous Materials of Plants. 



Academic des Sciences, June 14, 1847. — " M. Freray presented a 

 memoir upon a question which has occasioned much controversy 

 among chemists, namely, the nature of the gelatinous materials of 

 plants. He especially endeavours to show that it is no longer possi- 

 ble to confound pectine with the gums, mucilage, and above all, with 

 pectic acid, which is soluble in water. He describes many isomeri- 

 cal substances, and gives to each a new name. He distinguishes by 

 the appellation of pectose a substance which, like cellulose, is inso- 

 luble in water, alcohol and ether, and by the action of the weaker 

 acids is converted into pectine. It is chiefly found in the tissue of 

 vegetables, together with cellulose. According to M. Fremy pectose 

 occurs in the generality of fruits and roots ; and like diastose, it is 

 capable of forming, with the gelatinous substances of plants, a series 

 of isomerical metamorphoses. When a mixture of pectose and pec- 

 tine is inclosed in a flask and hermetically sealed, the pectine is seen 

 to be successively changed into pectosic, pectic, parapectic and me- 

 tapectic acids, without forming any secondary product. A.11 sub- 

 stances composed of carbon differ in composition solely in the ele- 

 ments of water which they contain. The author draws from his 

 researches this important physiological conclusion, that fruits, in 

 their progress towards maturity, pass through different intermediate 

 stages : — that pectose predominates in green fruits ; that in propor- 

 tion as maturity is attained, the pectose is changed into pectine ; and 

 that in fully ripe fruits, the pectine is in its turn converted into meta- 

 pectic acid." — Nouvelle Revue Encyclopedique, Juin, 1847. 



Occurrence of Juncus diffusus on Epping Forest. 

 By Edward Forster, Esq. 



Juncus diffusus, Hoppe, is to be found on Epping Forest, between 

 Walthamstow and Woodford, not far east of the seven-mile-stone, on 

 the New Road, and also in a wood hard by, called Great Shrubbush, 

 in the parish of Wanstead, growing intermixed with two or three va- 

 rieties of Juncus glaucus, the most green of which approaches it in 

 appearance, but may be easily distinguished by a proper attention to 

 the distinctive characters pointed out in the last edition of Babington's 

 Manual ; to which may be added, Juncus diffusus is a much more 

 Vol. II. 6 b 



