WATER ESSENTIAL TO ALL LIFE. 225 



to a limited extent. Examine carefully the capsule or husk 

 of a seed, and you will lind its structure well calculated to 

 resist for a considerable time external changes in temperature 

 and moisture. Study the groioing seed, and it will be found 

 to contain much water in its living growing part. The shell 

 or capsule, which exhibits great differences of structure in 

 various kinds of seeds, is very striking. After being fully 

 formed, the seed and its protective capsule gradually become 

 dry, and if you carefully moisten it, you may discover several 

 layers of different structure, one within the other. Each 

 layer consists of a number of little so-called "cells," each 

 cell in the dry state of each layer contains air. One cannot 

 easily imagine anything better as a non-conductor than this 

 arrangement of the " cells" of the capsule, by which the seed 

 is protected for a time from heat and cold, and its living- 

 germ preserved from action, it may be, for a long time. But 

 the seed, when kept moist or placed in water, will gradually 

 imbibe it, but the capsule in its dry state would keep out tlie 

 Avater for months. In some cases a long time passes before 

 it is moistened. The living embryo may, in fact, for a long- 

 time be kept from becoming too dry or too moist in very dry, 

 hot, or cold, or wet weather, by the remarkable structure of 

 the layers of its capsule. The common cocoa-nut is a seed 

 on a gigantic scale. Remove the very thick outside shell, 

 with its thick fibrous layer beneath, and you come to a shell 

 as hard as ivory, dead and most impermeahle. Within this is 

 a thick layer of moist firm tissue, which, as we know, may be 

 eaten, and within this is the so-called " milk " containing- 

 much water. The hte of the germ may be preserved without 

 much change for weeks, months, of years, and in some cases 

 probably for many years. 1 do not know that we can exactly 

 fix the limit of life in many instances, but there is something- 

 connected with the small vital germ of the seed by which 

 this is determined, for different germs may live in a quiescent 

 state for very different periods of time. Some seeds should 

 be planted very soon after their formation is complete, or 

 they will not germinate. Others will not grow until, as we 

 say, they are ripe. This power depends upon something in 

 the economy of the particular seed which is inherited. Some 

 seeds will not bear drought after they have once imbibed 

 moisture. Others will become dry and may get moist again 

 and again, without the death of the germ being caused, and 

 more than one kind of seed will bear frost and wet, and alter- 

 nate drought and cold during many months without its germ- 



