STRUCTURAL BOTANY. 



73 



embryo of Triglocliin ; 6, the same, transversely divided. 

 The EiiBRYo in the seed becomes a plant, provided it 

 meets with the conditions for its development. Within 

 the seed-coats we distinguish, as essentially permanent 

 parts, the plmnule and radicle, and as transient ones the 

 cotyledons, with more or less albumen, which gives nutri- 

 ment to the former, enabling them to grow. Their growth 



is what we call germination in general. The embryo may 

 break through the seed-coats, as soon as its root-end is 

 sufficiently developed, to draw food from the soil. (The 

 seed is then usually one year old.) But it will not escape, 

 until the seed is acted upon by moisture, with a certain 

 amount of heat, varying from 50° to 60° Fahr., and free 

 access of air. When separated from the plant and de- 

 prived of these conditions, its germinating power may 

 remain dormant for some time, without becoming finally 

 extinct. The seeds of certain leguminous plants have 

 been knowli to germinate after sixty years. According to 

 Lindley, raspberries were raised in the garden of the 

 British Horticultural Society from seeds, found with 

 the skeleton of a man, at the depth of 30 feet below the 

 surface of the ground, near Dorchester; and as coins of 

 the Emperor Hadrian were found together with the skele- 

 ton, it is supposed that the seeds were about 1600 years 

 old. In a more restricted sense, the term germination de- 

 notes the continued or renewed growth of the embryo in 



