SEEDS AND SEEDLINGS 



21 



and dew until germination actually begins. Plainly the 

 first need in this case is a root developed in tlie soil, 

 whence it may suck up the water and other substances 

 required for the con- 

 tinued growth of the 

 plantlet. To achieve 

 this object the caulicle 

 is pushed out of the 

 shell, and the radicle be- 

 gins to develop ; and at 

 once it may be seen that 

 the elongating axis mani- 

 fests something very like 

 a rudimentary sense, or 

 a number of senses. It 

 is affected by outward 

 influences. The radicle 

 of the oak is found, for 

 instance, to have been 

 turned sharply down- 

 ward ; or in many in- 

 stances the movement of 

 curvature has gone still 

 farther, and the grow- 

 ing radicle has followed 

 the under surface of the 

 shell backward to the 

 dampest spot in the im- 

 mediate neighborhood ; namely, the place where the acorn, 

 resting on the turf, has collected a little of the moisture 

 exhaling from the eartli — or at least preserved a humid- 

 ity higher than that of the open. Here the root has made 

 another turn, under the combined influence of gravity 

 and humidity, and has entered the soil (Fig. 10). 



23. The curvinof movements of the radicle are made a 

 little way back of the tip, and the growth of the latter is 

 thereby directed toward the proper surroundings. 



24. Seedlings from buried seed come into the air by a 



10. Germiuatioii of the White Oak. 



