JOO OF THE COTYLEDONS. 



tion, is lessened, and it becomes stunted and 

 dwarfish through its whole duration. 



Dr. Thomson of Edinburgh, in his System 

 of Chemistry, xoh 4, .374, has published a 

 very satisfactory explanation of one part of 

 the functions of the cotyledons. Several phi- 

 losophers have discovered that very soon after 

 the seed begins to imbibe moisture, it gives 

 out a quantity of carbonic acid gas, even 

 though no oxygen gas be present. In this 

 case the process stops here and no germina- 

 tion takes place. But if oxygen gas be pre- 

 sent, it is gradually absorbed in the same 

 proportion. At the same time the farina of 

 the cotyledons becomes sweet, being convert- 

 ed into sugar. " Hence, it is evident," says 

 this, intelligent writer, " that the farina is 

 changed into sugar, by diminishing its car- 

 bon, and of course by augmenting the pro- 

 portion of its hydrogen and oxygen*. This 

 is precisely the process of malting, during 

 which it is well known that there is a con- 

 siderable heat evolved. We may conclude 

 from this that during the germination of 



* This is also the opinion of M. de Saussure, Re- 

 cherches Chimiques surla Vegetation, p* 16. 



