GERMINATION. 73 



cific heat must be evolved; and this we find taking 

 place during germination, and is especially observable 

 during the malting of Barley, in which the grain attains 

 during the space of 96 hours an increase of tempera- 

 ture of 10 degrees, and afterwards, if the grain is not 

 turned frequently, it will rise as high as 80 Fah. 



18. Besides the necessity of the gaseous bodies we 

 have already spoken of, nitrogen seems also to be 

 employed during germination ; this was noticed by 

 Saussure in his experiments, who uniformly found that 

 azote was absorbed, though Priestley perhaps was the 

 first who remarked the circumstance. Boussingsalt has 

 lately confirmed the previous statements, and has come 

 to the conclusion that some plants derive azote from the 

 air, though others do not. 



19. We have stated that a certain degree of heat is 

 necessary for germination to ensue, and it is generally 

 said no seed will germinate at a temperature below the 

 freezing point of water ; Edwards and Collin say, not 

 below 44 Fah. ; Goeppert allows to 37 Fah. The sub- 

 ject requires further investigation in relation to some 

 cases, as in Nova Zembla, for instance, where plants 

 are to be seen in flower in a soil whose highest tempe- 

 rature at the time is only 34 Fah. According to the 

 last-mentioned observer no degree of cold can des- 

 troy the vitality of a seed, if it be perfectly dry, or have 

 absorbed no moisture. 



20. The degree of ascending temperature that seeds 

 will bear, is various ; some have borne that of 235 with 

 impunity, whilst 113 has been fatal to some; much 

 depends, however, on the hygrometric relations of the 

 heated air and seed : fluctuations of temperature are 

 generally detrimental. 



21. It being known what influence warmth, moisture, 

 and oxygen, etc., have upon germination, it has been 

 endeavoured to accelerate or retard the process by ar- 

 tificial means. Chlorine seems to accelerate it more 

 than any thing else ; as in a few cases also does the 



entle boiling of the seeds ; but atmospheres of pure 

 H 



