230 rHVTOCHE3IY. 



Mucilage passes into gum and starch. Into the former of 

 these it passes only after it has escaped from the plant, when it 

 is thickened by the influence of the oxygen of the atmosphere. 

 It then allows the azote to escape, which forms ammonia, or 

 the azote becomes united to lime, of which we find a consi- 

 derable quantity in gum. Gum has no longer the same ten- 

 dency to become putrid as mucilage. 



In tlie same manner starch is produced, probably from 

 a similar thickening of the mucilage, only this takes place in 

 the living plant ; because by the microscope we distinctly see 

 the grains of starch, like a deposit in the cellular texture. 

 Starch gradually passes, when mixed with water and ex- 

 posed to the M^arm air, into the acetous fermentation, during 

 which it becomes covered with mouldiness, 



352. 



Mucilage undergoes a further change when it passes into 

 saccharine matter. As, according to pretty good authorities, 

 saccharine matter consists of 74 parts of oxygen, 17 of car- 

 bon, and 8 of hydrogen, it is evidently formed by a higher 

 oxydation of mucilage, and, at the same time, by a change 

 in the proportions and quantity of hydrogen. The azote 

 seems in this case to have entirely vanished, since, during the 

 dry distillation, not a trace of it a])pears. From starch and 

 mucilage is formed sugar by oxydation. The tendency of 

 mucilage to oxydation favours the production of sugar. 

 When Beet, therefore, is exposed to the powerful action of 

 the sun's light, it affords less sugar, and it is accordingly 

 covered with earth to withdraw it from the light. When su- 

 gar is treated with spirit of wine, it loses its sweet taste, 

 and passes into the nature of gum. It is worthy of remark, 

 that saccharine matter, dissolved in water, undergoes the vi- 

 nous fermentation, which must arise from the disengagement 

 of hydrogen, and from a change in its proportions. Sugar 

 is produced in a dry and crystallised state, as a secretion 

 of some plants, and in union with quartz ; and in innumerable 

 plants, it appears as a honey juice or nectar, but, in these cases, 

 it is often united with the peculiar and even with the poison- 



