VEGETABLE PRODUCTS. 145 



water by which they are nourished passes through silicious soils. 

 Leguminous plants are decidedly partial to those waters which 

 contain lime in greater or less abundance. But the most decided 

 influence exerted on vegetables is that of salt-water. Many 

 species of vegetables cannot flourish when supplied with water 

 which does not hold salt in solution. These plants are such as 

 have soda as a necessary ingredient in their composition. 



277. Water also varies very much the texture of plants ac- 

 cording to the quantity which enters into the tissues. Those 

 vegetables which have leaves with few pores are succulent, with 

 loose distended cellular tissue, as in the Mesembryanthemum, 

 while in those furnished with abundant pores the tissues are 

 more compact and rigid. 



Some plants will live only in moist situations, while others 

 will avoid such localities, and flourish in dry sandy situations. 

 The Fungi requiring moisture are sent forth in profusion under 

 circumstances in which the Arenarias would perish from the 

 abundance of moisture. 



VEGETABLE PRODUCTS. 



For the benefit of those who may not have studied Chemistry, 

 we give the following brief explanations : 



278. An elementary body is one that has never been decom- 

 posed or reduced to a simple form, as Oxygen, Sulphur, Iron, 

 <fec. Each elementary body has a symbol, which is generally 

 the first letter, or first two letters of its English or Latin name. 

 The following are the symbols of the elements that enter into 

 the constitution of organic products, except some others in very 

 minute quantities. = Oxygen, H = Hydrogen, C = Carbon, 

 Ch = Chlorine, N = Nitrogen, S = Sulphur, P= Phosphorus, K 

 = Potassium, Xa = Sodium, Si = Silicon, Fe = Iron. Each of 

 these elements combines with any other element in a different 

 quantity, which is called its atomic weight. = 8, H=l, C = 

 6,C1=35.45,N=14,S=16, P=32, K = 40, Na=23, Si = 21, 

 Fe = 28. 



279. When any two or more combine we express their com- 



277. What effect on the tissue of plants ? What influences this ?— 278. 

 What is an elementary body ? Name the symbols of the elements that 

 enter into the constitution of" vegetable products? Their atomic weights? 

 —279. Express by symbols some compound bodies. 



