162 TOBACCO LEAF. 



constituents of the clay is altered when burned by a 

 gentle heat, and the substances which the plants require 

 are rendered more soluble. 



CARE OF PLANT BEDS. 



The covering, whether of glass or cloth, should be 

 removed after the plants are up, in the sunny part of 

 the day at first, and gradually for a longer time, until 



FIG. 24. FIELD READY FOB MACHINE TRANSPLANTING (Connecticut). 



finally no covering is used. This "hardening" process 

 is absolutely necessary, to give the plants sufficient 

 strength of constitution to withstand transplanting into 

 the open field, and to make a vigorous start when so 

 transplanted. The plants may be so uneven as to re- 

 quire that part be covered while the rest are exposed 

 (Figs. 15, 16, 17), but usually the entire covering is 

 removed (Fig. 19) after the sun is well up, but is spread 



