THE AWAKENING OF THE SEED 29 



Radish, Squash, etc. Such covers can absorb a large 

 amount of water even in a passing shower and hold 

 it after the surrounding earth is again dry. Many 

 seeds have spongy covers which act in much the same 

 way, as, for example, the Walnut, Hickory, Almond 

 (in which cases the spongy cover is usually removed 

 before the nuts come to market), Nasturtiums, etc. 

 The Walnut (Fig. 24), Hickory and Pecan have a 

 central, wick -like strand of absorptive tissue which 

 conveys the water directly to the germ, over the sur- 

 face of which it is spread out in a thin layer by means 

 of thin plates of absorptive tissue. In the grasses 

 and grain-plants the seeds are surrounded by parts of 

 the flower (the "chaff"), which assist greatly in soak- 

 ing up and retaining moisture, while the pulp of soft 

 fruits and berries serves the same purpose. In the 

 Castor -bean (Fig. 3) the large, spongy outgrowth at 

 one end (caruncle) serves the same purpose, as can 

 be shown by planting Castoi- beans deprived of the 

 caruncle alongside of unmutilated ones; its position is 

 such that the water passes from it directly through the 

 opening to the radicle, and it will be noticed that the 

 germ is attached to the cover only at this one point. 



We have now found out something about how the 

 seed gets water, and we can see clearly that, while 

 the need is the same in all cases, the means adopted 

 by different plants to supply this need are various; 

 in other words, the same problem is solved in a variety 



