CHAPTER II. 

 THE SEED AND ITS NEEDS. 



The Seed. — The seed is composed of three distinct parts: 

 (1) the embryo or vital center; (2) the protective coat; and 

 (3) the food materials. The seed is not a lifeless, inert 

 structure, as is thought by many, but, contrary to this belief, 

 it is definitely known that chemical changes are constantly 

 going on within the seed coat. The changes that are known 

 to take place are (1) water and carbonic acid gas are given 

 off, (2) a variation in the color of the seed, and (3) the food 

 materials are undergoing a gradual alteration. 



Germination. — Germination is the process by which an 

 embryo develops into a complete plant. It might also be 

 defined as the sprouting of a seed. Germination is said to 

 be finished when the seedling begins an independent exist- 

 ence. There are two distinct stages in the process of germina- 

 tion: (1) that marked by the appearance of the rootlets; 

 and (2) the subsequent development of the embryo into a 

 self-sustaining plant. Since the nourishment for the young 

 plant comes wholly from the seed during both stages, the 

 second stage in the process is quite as important as the first. 



In addition to the internal changes which go on there are 

 three distinct external conditions requisite to germination: 

 (1) the proper amount of water, (2) free oxygen or air, and 

 (3) an increase in the temperature. 



Water Necessary for Germination. — The amount of water 

 required to start the germination of a seed is that quantity 

 which will give complete saturation. This varies with the 

 seed. The amount of water absorbed also varies greatly 

 in the different climates, but it seems to depend upon two 

 conditions: (1) the character of the stored food and (2) the 

 amount of water already present in the seed. Some seed, 



