350 



CHANGES IN THE SEED DUEING GEKMINATION. 



He took 368 species of seed, fifteen years old, colleoted in the same 

 garden, and sowed them at the same time, and in the same circum- 

 stances as nearly as possible. Of the 368 only 17 germinated, and com- 

 paratively few of the species came up. The following are the results : — 



Per cent. 

 0-60 

 0-20 

 0-03 

 0-00 

 0-00 

 0-00 

 0-00 

 0-00 

 0-00 



In 357 species, of which the duration of life was known, the results 

 were : — 



Per cent. 

 Annuals ... 9 came up out of 180 species . . 5'0 

 Biennials. . . ,, ,, 28 „ . . O'O 



Perennials . . 4 ,, ,, 105 ,, . . 3'8 



Ligneous . . . 3 ,, ,, 44 ,, . . 67 



16 



357 



4-4 



Ligneous species thus seem to preserve the power of germinating 

 longer than others, while biennials are at the opposite end of the scale j 

 perennials would appear to lose their vitality sooner than annuals. 

 Large seeds were found to retain the germinating power longer than 

 small ones, and the presence or absence of separate albumen or perisperm 

 did not seem to make any difference. Oompositae and Umbelliferse 

 lost their germinating power very early. From these experiments 

 DecandoUe concludes that the duration of vitality is frequently in an 

 inverse proportion to the rapidity of the germination. 



Chemical Changes during Germination. — During the process 

 of germination certain changes take place in the contents of the seed, 

 by which they are rendered fit for the nourishment of the embryo. In 

 exalbmninous or aperispermic seeds, where the embryo alone occupies 

 the interior, these changes are effected principally in the matters stored 

 up in the cotyledons. In albuminous or perispermic seeds, on the 

 other hand, the changes occur in the substance of the perisperm. One 

 of the most remarkable of these changes is the conversion of starch into 

 dextrine and grape sugar by a process of oxidation, the object being 

 the conversion of an insoluble into a soluble substance. While this 

 conversion of starch into sugar proceeds, oxygen is absorbed, carbonic 

 acid is given off, and heat is produced. It is probable that at this 

 period there is a certain amount of electric disturbance. Carpenter 

 states that the conversion of the starch of the seed into sugar involves 



