CH. I.] SOWING. 17 



indeed may be employed Avith great advantage, 

 when the seed from age or other cause geinninates 

 A\-ith difficulty. Dr. Lindley foimd the seeds of a 

 raspberr}^ germinate, though they must have endured 

 a temperature of 230'^ in the boiling synip of the 

 jam, -whence they were taken ; and other instances 

 are known where peas submitted to a temperature 

 of 200°, and, left in the water for twenty-four 

 hours until cool, germinated more readily than 

 other peas not so treated. The seeds of Acacia 

 lophantha also produced seedlings after being boiled 

 in water for five minutes. The effects produced by 

 this high temperature, are to permanently soften the 

 cuticle of the seed, and render it more readily per- 

 meable by the air ; also aiding the conversion of the 

 starchy components of the seed into saccharine 

 matter ; but if the boiling be contmued until the com- 

 position of the germen is altered, the germinating 

 power of the seed is destroyed. 



These facts lead to the verj- important inquiry, 

 whether the soil has any influence over the tempera- 

 ture occurring to the seed, and to the roots of plants 

 placed beneath its surface. The researches of M. 

 Schluber answer this query in the affirmative. This 

 distinguished German chemist fomid that when the 

 temperature of the upper sui'face of tlie earth was 77° 

 in the shade, various soils, exposed to the sun from 



c 



