GEBMIKATION. 357 



ferences in development disappeared before the plants 

 blossomed. 



On the other hand, Grouven, in trials with sugar-beet 

 seed — made, most jrobably, in awell-manured and rather 

 heavy soil — found that sowing at a depth of three-eighths 

 to one and a fourth inches gave the earliest and strongest 

 plants ; seeds deposited at a depth of two and a half 

 inches required five days longer to come up than those 

 planted at three-eighths of an inch. It was further shown 

 that seeds sown shallow, in a fine wet clay, required four 

 to five days* longer to come up than those placed at the 

 same depth in the ordinary soil. 



Not only the character of the soil, which influences the 

 supply of air and warmth, but the kind of weather 

 which determines both temperature and degree of moist- 

 ure, have their effect upon the time of germination, and 

 since these conditions are so variable, the ruleS of prac- 

 tice are laid down, and must be received, with a certain 

 latitude. 



§4- 



THE CHEMICAL PHYSIOLOGY OF GBRMIITATION. 



The Nutrition of the Seedling. — The young 

 plant grows at first exclusively at the expense of the 

 seed. It may be aptly compared to the suckling animal, 

 which, when new-born, is incapable of proyiding its 

 own nourishment, but depends upon the milk of its 

 mother. 



The Nutrition of the Seedling falls into three pro-' 

 cesses, which, though distinct in character, proceed sim- 

 ultaneously. These are : 1, ^Solution of the Nutritive 

 Matters of the , Cotyledons or Endosperm ; %, Transfer ; 

 and 3, Assimilation of the same. 

 ' 1. The Act of Solution has no difiiculty in case of 



