76 BOARD OF AGRICULTURE. [Pub. Doc. 



properties or qualities which the green leaf does not possess, 

 and also a loss in weight in the dry leaf in addition to the 

 loss of water. 



In order to understand something of the changes which 

 take place in curing, it is necessarj' to consider for a moment 

 the plant as it matures and ripens in the field. The leaf 

 may be considered the factory in which is manufactured 

 from the raw materials absorbed from the air and soil the 

 food supply whicli enables the plant to grow, to " ripen/' as 

 we say, and to produce seed. The energy to operate this 

 factory, so to speak, comes from the sunlight, and during the 

 day, especially on sunshiny days, the food supply accumulates 

 in the leaf. During the night, however, the building up of 

 food stops, and the accumnlated food supply, excepting of 

 course such as is required for the leaf itself, is carried away to 

 other parts of the plant, such as the very young parts and the 

 seed head. This explains why topping and suckering cause 

 the leaf to spread and to take on more body, for, the seed head 

 and suckers being removed, the food materials collect in the 

 leaf in greater quantity. One important feature of ripening, 

 therefore, is the accumulation in the leaf of certain food mate- 

 rials which it has built up. These materials are chiefly of a 

 starchy nature, and tend to make the leaf brittle and more or 

 less woody or strawy. We must remember, moreover, that 

 plants must breathe or respire the same as do animals, and 

 this breathing or respiration process also uses up a large por- 

 tion of the food supply. The two uses of the food supply 

 built up by the leaf are, accordingly, to promote growth and 

 to maintain the breathing or vital processes of the plant. 



We have seen that the leaves of the plant when ready for 

 harvesting have accumulated an excess or reserve food supply, 

 chiefly of a starchy nature, which gives to the ripe leaf its 

 characteristic properties. We are now in a position to con- 

 sider what happens in the curing barn. It has already been 

 stated that a leaf quickly dried out does not show the proper- 

 ties of cured tobacco, and it is impossible to cure such a leaf. 

 Again, if a green leaf be exposed to chloroform vapors for a 

 short while, which quickly kills it, the leaf can never be cured 

 successfullv. The same is true of a bruised leaf, and we are 



