440 NATURAL HISTORY OF PLANTS. 



Bedeguars or moss-galls, several Brambles, Agrimonies, and Al- 

 chemils, Dropwort, and several other species of SpircBci. 



Another product of the bark of Bosacea is gum, whose forma- 

 tion results from a morbid condition' in most of our wild or cultivated 

 Prunece, especially the common Plum, the Apricot, and the two com- 

 mon Cherries. In many of these trees as they grow old it exudes 

 spontaneously from the stem and boughs. This gum (known in 

 France as gomme de France or nostras), imperfectly soluble in water, in 

 which it swells out considerably, is no longer employed in medicine, 

 and is only used in preparing felt for the hatter. The best known is 

 that found in large quantities in the superficial integument of Quince 

 pips," which is much used as a demulcent in medicine, and in arts and 

 domestic economy for its glutinous properties. Next to gums come 

 the forms of mucilage so abundantly produced in several Rosacece. 

 Apple and Pear pips may also supply a small quantity of this muci- 

 laginous substance ; but it is especially abundant in the barks of the 

 diflferent soap-Quillais, especially QiiiUaja Saponaria,^ Smegmadermos* 

 and brasiliensis.^ It is probably the bark of one of these, perhaps the 

 first, which is often sold in Paris under the name of eco7'ce de Panama 

 (Panama Bark). Powdered and mixed with water this substance 

 makes it froth like soap-suds, and gives it the property of removing 

 grease from woollen and silk stuffs.^ 



' See A, TEfCTTL, Malad. de la Gomme chez for gum-channels are folds in the cell-membranes. 

 les Cerisiers, Us Pruniers, les Abricotiers, les In the Apricot these cells are often dilated, and 

 Amandiers (Compt. Send, de I' Acad, des Sc., li. form necklaces, between the beads of which are 

 624) ; Product, de la Gomme chez le Cerisier, septa, which may be more or less completely 

 le^ Prunier, I'Amandier, I'Abricotier, et le Pecker absorbed. These cavities and those of the woody 

 (I'Instit., XXX. n. 1490, 241). The gum was fibres themselves in certain Pruneee may contain 

 formerly believed to be secreted by the cells of not only gum but alsocerasome,a substance which 

 the inner bark of these plants. It was sup- is neither gum nor cellulose, and is not acted 

 posed to be deposited in the outer cellular tissue, upon by iodine or sulphuric acid even after boil- 

 and when the bark is finally torn open, to flow ing in potash. In the cavities of the sap wood 

 out. KuETZiNG announced in 1851 that the we also find around the true gum another sub- 

 cellulose membranes might be transformed into stance, which does not swell up in water, and 

 gum. In 1857 Karsten affirmed that all gums turns bright pink in contact with iodine and 

 and mucilages were the result of some such sulphuric acid. 



change. Wigand, in the first part of his ^ Cydonia vulgaris Pers. (p. 395, figs. 463- 



memoir, Ueber die Deorganis. der PJlanzenz. 465). The fruit is the Cydonia or Cotonea of 



(Pringsh. Jahrb., iii. 115), studied the transfor- pharmacopeias and the Kvh^via of Hippocrates, 



mation of the tissues of the wood and bark of ^ moi,., Chil., ed. 2, 298.— (^. I MolincB DC, 



Rosacea!. TuicUL thinks this gum is a purely Prodr., ii. 547, n. 2. 



pathological product cxtravasated into equally ■• DC, loc. cit., n. 1.— (^. Saponaria Poir., 



morbid cavities. Under the influence of a too Did., vi. 33 (ncc Mol., ex DC), 



large supply of nourishment the young cells of * Mart., S^sL Mat. Med. Bras., 127.— Fan- 



the generative layer may be absorbed ; the ieyiellea bras'ilioisLs- A. S. H. & TUL., Ann. Sc. 



vessels may bo similarly destroyed, and so form Nat., ser. 2, xvii. 141, t. 7. 



cavities, on the walls of whicli appears the gum, s 'p,,;^ property seems due to a peculiar pun- 



which thence spreads into tlie neighbouring an- gent substance, which Boutron & Henut 



tractuosities. The striie whicli liave been taken (Joiirn. de Pharm., xiv. 247 ; xix. 4) have found 



