1887. | BOTANICAL GAZETTE. 55 
tion. The chief obstacles to successful sugar making have 
been, frst, unfavorable climatic conditions ; second, imper- 
fect methods of extracting the sugar; ¢A7rd, improper treat- 
ment of the extracted juice; fourth, variations and rapid 
changes in the sucrose of the juice. All of these problems 
have been successfully solved save the last. It is proper to 
say, however, that certain methods of cultivation and certain 
methods of selecting seeds tend to produce maximum con- 
tents of sucrose in the cane and these methods are not yet 
fully developed. A proper conception of the variations to 
which the sucrose in sorghum is obnoxious can not be had 
unless we study briefly the method of its formation, how it is 
stored and the physiological functions in which it takes part. 
Vegetable physiologists have taught us that a carbo- 
hydrate can be formed by a certain retrogressive change in 
protoplasm, by which the cell envelope, in other words cellu- 
lose, is produced. The carbohydrates which appear in the 
embryo of a plant are developed at the expense of the stores 
of material in the seed. After the appearance of the chloro- 
phyll cells in the plant the production of carbohydrates takes 
place with their aid, CO, being absorbed from the air and 
free oxygen being eliminated. _ 
t would be easy to explain the production of carbohydrates 
by Supposing that the chlorophyll cell exerted a reducing 
influence’ on the CO, which, with the assimilation of water, 
produced, for instance, starch by the formula 6CO,-+-5H, 
=C€,H,,0;+0,,. In the vast majority of plants it is found, 
i corroboration of this supposition, that the volume of the 
Oxygen set free is sensibly the same as the carbonic dioxide 
absorbed. he carbohydrate which is generally formed in 
the chlorophyll cells is starch. This starch is removed 
from the leaf, and it is supposed that the carbohydrates which 
are formed in all parts of the plant are derived from this 
original substance. 
in point of fact, however, the production of organic mat- 
ter in a plant does not probably take place in the simple 
Manner above described. It is more likely that the presence 
of a nitrogenous body is necessary and this proteid itself is 
the active principle of the production of new organic matter, 
Y @ certain decomposition it suffers, with the help of carbonic 
dioxide and water. Nor is it by any means certain that 
Ut has lately been stated that this reduction is due to the action of electricity on the 
Jeaf—producing hydrogen—-and this hydrogen is the active principle in the reduction of 
he carbonic dioxide. This statement to be purely theoretical. 
re 
