INTRODUCTION. 



to it ; that the flower of one plant should be crimson, 

 that of the next yellow ; that one should delight us 

 with its perfume, and that the very next one should 

 offend us by its fetor ; or that a food, a medicine, 

 or a poison, should be found the closest neighbours. 

 Nor is it less singular that light, which is so necessary 

 to the growth of plants that without it they lose those 

 substances upon which their colours depend, and be- 

 come pale and sickly, is unfavourable to the germina- 

 tion of seeds. And yet the matter is no prodigy, but 

 depends upon principles which hold true in the animal 

 and the mineral kingdom as well as in the vegetable. 

 The moisture and the exclusion of light bring on a 

 fermentation, in the course of which, the farina of the 

 seed is converted into sugar ; the very same process by 

 means of which malt is made out of barley. The 

 colouring matters again are all oxides, or combinations 

 of oxygen, in some way or other, and have a very great 

 resemblance to the artificial colours which chemistry 

 has taught mankind to prepare. The colours of all 

 flowers are more intense in fine sunny weather ; the 

 skins of the inhabitants of warm countries become 

 dark ; those who are exposed to the sun in summer, 

 become brown. 



In this single department of one of the kingdoms of 

 nature, we have thus not only a fund of the most 

 curious information, but of information that is prac- 

 tically useful at every step. Even from the mere form 

 of vegetables, we have some of the choicest of our 

 ornaments, and have taken some of the most useful 

 hints in our architecture. The engineer who first suc- 

 ceeded in fixing upon the dangerous rocks of Eddy- 



