A POPULAR STUDY. 315 



final decay of the old plant. In a thousand plants 

 of the same species we can thus observe a thousand 

 points in the history of the same plant ; and thus 

 we have, before our eyes, as clear and satisfactory 

 information as if we could work the seed up to the 

 plant, or change the plant back to the seed by direct 

 experiment, in the same way that we can dissolve 

 or form a chymical compound. It is true that we 

 cannot, in the case of the vegetable, keep the sub- 

 stances out of which it is immediately compounded 

 in boxes and bottles, or pour the water directly out 

 of a pitcher, or apply the fire directly by a furnace, 

 in the same manner as we can do in the chymical 

 experiment ; but still we can " watch the progress" 

 as closely in the one case as in the other ; and we 

 have no more knowledge of the ultimate principles 

 of chymical union than we have of vegetable as- 

 similation. 



From what we do observe, however, we can 

 accelerate, retard, and otherwise modify the action 

 of vegetables over a very considerable range. It is 

 upon our power of doing this that all cultivation, 

 whether of the fields, the garden, or the forest, is 

 founded ; and that cultivation may be said to be the 

 groundwork of all that we do and all that we can 

 possess. Our food is either directly vegetable or 

 obtained by means of vegetables. The corn, the 

 pulse, the roots, the buds, the leaves, and the fruits, 

 which, in their immediate substance, prepared or 

 unprepared by art, human beings use for food, are 

 very numerous ; so much so that the list of those 

 which are familiarly known in the British markets 

 would fill a considerable volume ; and when those 

 that are used in other countries are added, the num- 

 ber is almost incredible. 



When a number of species, having those appear- 

 ances, which lead botanists to consider them as 

 " allied," and form them into what they call a " natu- 

 ral order" (there are no orders or classes in nature^ 



