GERMINATION OF THE SEED. 



135 



Fig. 88. 



Bursting through the 

 coats which surrounded it, 

 and which are already 

 enfeebled by their loss of 

 carbon, the embryo emer- 

 iges from its prison, the 

 \radicle shoots downward, 

 and the plume rises up- 

 wards. We say then that 

 the seed has come up or 

 sprouted. Fig. 88 repre- 

 sents a young dicotyle- 

 donous plant, with its ra- 

 dicle, a, developed ; its 

 plume, &, is yet scarcely 

 perceptible ; its cotyle- 

 dons, c, appear in the 

 form of large, succulent 

 seed-leaves. The radi- 

 cle, or descending root, 

 is usually the first to break 

 through the coats of the seeds; it commences its journey 

 downwards, to seek in the earth nourishment for the future 

 plant, and to fix it firmly in the earth. This constitutes the 

 root, and always takes a downward course, in whatever situa- 

 tion the seed may have been placed in the ground. 



A botanist once planted in a pot, six acorns, with the points 

 of their embryos upwards. At the end of two months, upon 

 removing the earth, he found that all the radicles had made an 

 angle in order to reach downwards. It is supposed that if the 

 root met with no obstruction in going downwards, it would al- 

 ways be perfectly straight. 



Fig. 89 is the representation of 

 a germinating seed of the mirabalis 

 (four o'clock) ; it will be seen that 

 the radicle, a, has made nearly a 

 right angle in turning downwards ; 

 the plume is not developed. 



If you put cotton into a tumbler of 

 water, and place upon it some seeds 

 of rye or wheat, which soon vege- 

 tate, you will see all the fibres shooting from the seeds, in a 

 perpendicular direction, downwards. It is a very simple and 



Experiment with acorns Explanation of Fig. 89 Seeds placed on cotton 

 in a tumbler. 



