VEGETABLE ORGANIZATION. (>l 



been supposed to perform, as will hereafter be seen, 

 an important part in the function of nutrition. 



Fluids of various kinds occupy both the cells and 

 the intercellular spaces. The contents of some is 

 the simple watery sap ; that of others consists of 

 peculiar liquids, the products of vegetable secretion : 

 and very frequently they contain merely air. In 

 many of the cells there are found small opaque and 

 detached particles of the substance termed by 

 chemists Fecula, of which starch is the most com- 

 mon example, and which is distinguished by the 

 property of becoming blue when acted upon by 

 iodine. 



The material which gives to the different parts 

 of plants, and more especially the leaves, their green 

 colour, is a peculiar resinous substance, termed 

 Chloropliyllite^' or Chromulite.\ It sometimes oc- 

 curs as a semi-fluid gelatinous substance, having 

 no determinate figure : but its more usual form is 

 that of globular grains, intermixed with the colour- 

 less fluid of the cells. Mohl has discovered that 

 each of these globules contains one or more granules 

 of fecula, varying in size from the .3,600th to the 

 60,000th part of an inch in diameter, around which, 

 as on a nucleus, the chlorophyllite appears to have 

 been deposited ; for he found that the central gra- 

 nules acquire a blue tinge by the action of iodine, 

 while the same agent renders chlorophyllite brown.] 

 In the autumn, when the leaves decay, the fecula 

 is found to have disappeared, and the chlorophyllite 

 to have acquired a yellow colour. 



* Pelletier and Caventou, Ann. Ch. and Phys, ix. 194. 



f De Candolle, ib. xxxviii. 422. 



\ Ann. Sc. Nat. serie 2. Bot. ix. 162. 



