16 INFLUENCE OF WATER AND HEAT UPON GERMINATION. 



of a mucilaginous saccharine secretion which the germinating 

 seed possesses the power of forming. With the assistance of 

 this substance, the root, technically called the radicle, at first a 

 mere point, or rather rounded cone, extends and pierces the 

 earth in search of food ; the young stem rises and unfolds its 

 cotyledons, or rudimentary leaves, which, if they are exposed to 

 light, decompose carbonic acid, fix the carbon, become green, 

 and, by processes hereafter to be explained, when speaking of 

 leaves, form the matter by which all the pre-existing parts are 

 solidified. And thus a plant is born into the world ; its first 

 act having been to deprive itself of a principle (carbon) which, 

 in superabundance, prevents its growth ; but, in some other 

 proportion, is essential to its existence. 



