54 BIOLOGY OF PLANTS. 



conveyed into the organs of nutrition. As soon as this stored 

 nutriment is exhausted, the diastase itself is transformed, and 

 enters into the plant. 



6. ^rr^/r «f?'c? is also formed in the process. This is proved 

 by the fact, that when seeds are made to germinate in pow- 

 dered chalk, after a little while, acetate of lime may be wash- 

 ed out from it. This substance is very soluble in water, and 

 the agency of the acid according to Liebig is to combine 

 with lime and earthy substances, and convey them into the 

 roots of plants. But since the experiments of Braconnot ren- 

 der it probable that acetate of lime is injurious to plaAts, this 

 special function of the acid may well be doubted. It may aid 

 in converting cane sugar or starch into grape sugar, as it is 

 fully established that such changes take place, when these 

 substances are brought into contact with a dilute acid. When 

 the sprout starts up, the sugar, under the influence of light, is 

 converted into looody fhre. This does not take place until 

 the true or second leaf is expanded. 



The period required for the germination of various seeds, 

 when the requisite conditions are supplied, depends upon the 

 nature of the plant, that is, upon the peculiar constitution or ac- 

 tivity of the vital principle. The vitality of some seeds, like that 

 of the smaller grains, peas, etc. are quickly excited ; those of 

 corn, and most of the vines require a longer period ; while the 

 stone fruits, and many of the nuts, require wrecks, and even 

 months, before they will indicate any signs of life. 



The germination of seeds may be promoted by adding sub- 

 stances to them, either before, or after they are sown. 



1. Immersing seeds in hot water has been found to pro- 

 mote germination. This is particularly desirable in the case 

 of parsnips, carrots and beets, whose vital powers are not 

 easily excited by the ordinary temperature and moisture. 



2. Mr. Bowie states, that " he found the seeds of nearly all 

 leguminous plants germinate more readily, by having water 

 heated to 21)0°, or even to the boiling point of Fahrenheit's 



