SAP, SUGAR, ETC. 53 



growth (27 - 40) : others require a brief notice here, especially two 

 soUd products which are of nearly universal occurrence and of 

 great importance in the vegetable economy, namely. Chlorophyll and 

 Starch. 



78. The same cells contain liquids, solids, and air, at different 

 ages. Growing and vitally active cells are filled with hquid (at 

 least while vital ojjerations are carried on), namely, with water 

 chai'ged more or less with nutritive assimilated matters, the pre- 

 pared materials of growth (11, 27). Any air they may contain at 

 tliis period is, for the most part, held in solution. Completed cells 

 may still be filled with liquid, or with air, or with solid matter only. 

 The liquid contents of the vegetable tissues, of whatever nature or 

 complexity, are generally spoken of under the common and some- 

 what vague name of 



79. Sap. Li employing this name we must distinguish, first, 

 Crude Sap ; the liquid wliich is imbibed by the roots and carried 

 upwards through the stem. This is water, impregnated with certain 

 gaseous matters derived from the air, and with a minute portion of 

 earthy matter dissolved from the soil. It is therefore inorganic (12). 

 But, as it enters the roots and traverses the cells in its ascent, it 

 mingles with the Hquid or soluble assimilated matters Avhich these 

 contain, so that unmixed crude sap is never met with in the plant. 

 On reaching the leaves, a part of the inorganic materials of the 

 ascending sap are transformed, under the influence of hght, into 

 organizable or assimilated matter ; and the liquid, thus charged Avith 

 the prepared materials of growth, is now Elaborated Sap. The 

 nutritive matter of the elaborated sap is of two general kinds : 

 1. The ternary, which consists of only the three elements, carbon, 

 hydrogen, and oxygen; and 2. The quaternary, which consists of 

 four elements, viz. of nitrogen in addition to those just mentioned. 

 Sugar and dextrine, or dissolved stai'ch, are representatives of the 

 first class ; mid these have nearly the same chemical composition as 

 cellulose or cell-membrane. Protoplasm or proteine represents the 

 Second class (27). 



80. Sugar (of which there are two distinct kinds, Caiie and Grape 

 Sugar) is the most soluble form of ternary organizable matter. 

 Though sometimes crystallized as an excretion in the nectai'ies of 

 flowers, yet in the plant it exists only in solution. It abounds in 

 growing parts, in many stems just before flowering, as those of the 

 Sugai'-cane, Maize, Maple, &c., in pulpy fruits, and in seeds when 



5* 



