34 GERMINATION. 



we learn how these vessels are tinged when the germi- 

 nating seed is placed in a coloured fluid, and why the 

 young plant inevitably dies if the cotyledons are pre- 

 maturely removed. 



But the fluids thus imbibed by the seed do not reach 

 its embryo unchanged. They dissolve the farina of the 

 albumen or lobes, a quantity of carbonic acid gas is 

 disengaged, and a fermentation is thus begun which ter- 

 minates only in the evolution of the new plant, or in 

 the destruction of its vitality. If no oxygen gas be 

 present, the latter consequence ensues, for whether it 

 stimulates the vital principle, supplies the embryo with 

 food, or converts the farina of the cotyledons into a 

 mild and nutritive substance resembling sugar, whatev- 

 er be its mode of operation, the importance of this 

 agent, nay its necessity to germination has been most 

 fully established. 



By removing even a minute portion of its carbon, the 

 farina of seeds is converted into sugar, and from the 

 very luminous experiments of the younger Saussure it 

 has been reasonably inferred that oxygen promotes the 

 germination of seeds only as it combines with their car- 

 bon, and enables it to escape. Thus by a process near- 

 ly allied to that of malting, the infant plant is supplied 

 with food, and it is probable that in the former as well 

 as in the latter case, a small portion of heat is disengag- 

 ed. "I conceive" says Dr. Smith, " the evolution of 

 this heat may powerfully further the progress of vege- 

 tation, by stimulating the vital principle of the embryo, 

 till its leaves unfold and assume their functions." — 

 Whether this conceit be true or not, it is certain that 

 germination may be much advanced by the application 

 of artificial heat, and seeds have in this way been made 

 to vegetate in three hours, which under ordinary ch 



