45 



in the manner abeady described under the heading, 

 Root, Stem, &c. 



It has been remarked that seed con- 

 tains the rudiment of a plant similar to 

 that on which it is produced ; but this 

 needs some explanation. In distinct 

 S2:>ecies, this will be time ; but the seeds 

 of varieties that have been produced 

 by culture and hybridizing, seldom or 

 never reproduce exactly their like, 

 hence the necessity for the various 

 artificial methods of multiplication, 

 such as grafting, budding, layering, 

 &c. It is to these operations that we 

 are indebted for the preservation of 

 varieties that were originated hun- 

 dreds of years ago. 



Germination. — Heat and moisture, 

 air, and the exclusion of light, are all 

 necessary to the healthy and perfect 

 germination of seeds. It may be well to consider, briefly, 

 the part which each of these has to perform. 



1st. Moisture. — When seeds are sown in a time when 

 the groimd is parched, they will show no signs of germi- 

 nation until it is, in some way or other, moistened. The 

 quantity of moisture necessary to a seed depends on the 

 natm-e of its covering and its size. A small seed, with a 

 thin covering, will vegetate much sooner and with less 

 moisture than a large seed, with a hard, bony covering. 

 The moisture must, in the first place, soften the covering, 

 penetrate to the mealy part of the seed, and prepare it 

 for the chemical changes necessary to convert it into food 

 for the embryo plant. If apple or pear seeds be kept in 

 a dry, warm room all winter, they will not be likely to 

 vegetate the following spring, but if sown will probably 



Fig. 55. 



Fig. 55, germinating 



seed, a, plumule, b, 



radicle, c c, cotyledons. 



