GERMINATION. 49 



absorbed by water. In its pure state it is a powerful alkali, of 

 a caustic and burning taste, and pungent odor.* 



It resembles water in the circumstance of being easily de- 

 composed in the vegetable organs. The alkahes are tested by 

 their turning vegetable blue c(>lors green. Acids are tested by 

 their inij)arting to the same vegetal)le infusions a red color. 



With these definitions and descriptions the reader is prepar- 

 ed to attend to the sidjject of this section. 



Germination. The development of vitality in the seed, or 

 germ, is called the process o{ germination^ by which process 

 the embryo is extracted from its envelopes, and converted 

 into a plant. The conditions necessary to excite the vitality 

 of the seed are three : access to moisture, to air or oxygen 

 gas, and to heat. 



1. Moisture. Seeds which are fully matured and dry will 

 retain the vital power in an inactive state for a long time, if 

 no water is present, because this agent is necessary to facili- 

 tate the chemical changes which must take place, before it 

 can be called into action. The first effect produced by wa- 

 ter, is to penetrate the outer covering of the seed. The effect 

 is purely physical, and takes place equally well in the dead 

 and living seed. A grain of wheat, or corn, for example, de- 

 prived of its vital principle, will absorb water, and become 

 putrescent, while one which still possesses vitality will, by 

 imbibing moisture, develope a succession of new and living 

 powers. The second effect of water, is to yield oxygen to the 

 carbon of the germ, and form carbonic acid, which soon en- 

 velopes the seed. The decomposition of the water is effected 

 by the vital power of the seed. The hydrogen of the water 

 is supposed to combine with the oxygen of the air,' and form 

 water again. Few seeds, however, will complete the process 

 of germination, when wholly immersed in water, especially if 

 air is excluded ; hence the injurious influence of a very wet 

 soil, or a wet season, at the time of planting the seed. 



* For a fuller description of the simple and compound bodies, see 

 Gray's Chemistry, 



