THE RESERVE MATERIALS OF PLANTS. 61 



The glucosides that have attracted most attention during 

 recent years are those which occur in the plants belonging to 

 the families already mentioned, the Rosacese, the Cruciferae, 

 and other orders which show affinities with these. These 

 plants contain, very widely distributed through their tissues, 

 amygdalin and sinigrine or myronate of potash respectively. 

 Of these the former is perhaps the most interesting, as 

 from its decomposition by enzyme agency there is produced 

 hydrocyanic acid, which has always been regarded as most 

 virulent in its action upon all living things. The existence 

 of this noxious principle in the plant has perhaps been partly 

 the cause of the readiness of botanists to class the glucoside 

 which yields it, and hence the whole class of glucosides, 

 among the products of excretion. 



The localisation of the amygdalin is calculated to throw a 

 good deal of light upon the question of its probable function 

 and fate. For many years attention has been given to it, 

 at first, owing to imperfect methods of research, without 

 much practical result. Improvement in technique has, 

 however, yielded very valuable results, and has led to 

 conclusions greatly at variance with those held thirty 

 years ago. Thome (60), who wrote in 1865 upon the 

 nutritive materials contained in the sweet and bitter al- 

 monds respectively, said that amygdalin occurs in the 

 parenchyma of the cotyledons of both varieties, and that 

 its corresponding enzyme, emulsin, is only present in the 

 bitter almond, being localised in the weak fibrovascular 

 bundles that are in the cotyledons. This statement has 

 been shown to be the exact converse of the truth. Portes 

 (61), who worked twelve years later, showed that the gluco- 

 side and the enzyme occupy different parts of the seed, the 

 former being distributed in the cotyledonary parenchyma, 

 while the latter is to be found in the axis of the embryo. 

 Pfeffer (62), in his Pflanzenphysiologie, suggests that this 

 localisation is not accurate, and that the two bodies probably 

 occupy the same cells, the only degree of separation being 

 that the ferment is in the protoplasm and the glucoside dis- 

 solved in the cell-sap. In 1887 Johansen (63) by chemical 

 methods succeeded in ascertaining the distribution of the 



