Page:An introduction to physiological and systematical botany (1st edition).djvu/130

 100, is lessened, and it becomes stunted and dwarfish through its whole duration.

Dr. Thomson of Edinburgh, in his System of Chemistry, vol. 4, 374, has published a very satisfactory explanation of one part of the functions of the cotyledons. Several philosophers 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 germination takes place. But if oxygen gas be present, it is gradually absorbed in the same proportion. At the same time the farina of the cotyledons becomes sweet, being converted into sugar. "Hence, it is evident," says this intelligent writer, "that the farina is changed into sugar, by diminishing its carbon, and of course by augmenting the proportion of its hydrogen and oxygen . This is precisely the process of malting, during which it is well known that there is a considerable heat evolved. We may conclude from this that during the germination of