PHYSIOLOGY OF THE SUGAR CANE, 



25 



A transverse section of the cane shows the divided longi- 

 tudinal tubes, presenting a cellular structure, and filled with 

 a transparent fluid. Most of these cells contain a pure solu- 

 tion of sugar, which varies in density with the age of the 

 cane, and the circumstances affecting its growth. There 

 are also sap-vessels containing in solution the elementary 

 substances required for the growth of the plant. These 

 lie parallel to, but have no communication with, the cells 

 containing the sugar, and convey the circulating sap from 

 the roots to the upper extremities of the plant. 



The whole of the surface of the stem is coated with a 

 thin siliceous crust or glaze, on portions of which, par- 

 ticularly near the union of the joints, and in some varieties 

 of canes more than others, there is formed a small 

 quantity of a kind of wax, known as cerosie or cerosine. 



It must be borne in mind that no uncrystailizable sugar, 

 glucose, or melasses, pre-exists in the cane, the whole of 

 the sugar being crystallizable, and of the variety known to 

 the chemist as cane sugar. 



The process by which the sugar is elaborated and 

 deposited in the cells of the plant, is one of those inscrut- 

 able mysteries of nature which have hitherto baffled the 

 researches of scientific men ; but its composition, and the 

 purpose for which it exists in the cane, are clearly under- 

 stood, being evidently intended to yield material for the 

 progressive development of the plant during its growth, as 

 when the cane is growing rapidly, its juice contains but 

 little sugar, that substance being required as fast as it is 



