54 BOAED OF AGRICULTUEE. 



continuation of its kind. This may be followed by immediate 

 death and decay, as in the mushroom and century-plant, or, 

 as in most perennials, growth and fruiting may go on together 

 for many years, and the decline of the vital force be gradual. 

 In the simpler forms of vegetation we find great uniformity of 

 structure, even when the individual attains an enormous size, as 

 in the gigantic kelp of Cape Horn, which reaches a length of 

 several hundred feet, but shows no distinction of vegetative 

 organs. If, however, we plant the seed of an apple, and 

 watch its progress from germination to maturity, we notice at 

 once several sets of organs with distinct forms and functions. 

 The young tree has a root which avoids the light and pene- 

 trates the soil in all directions where the conditions are suit- 

 able. It has a stem of curious construction which rises from 

 the ground, lifting its head high into the air. It is covered 

 with leaves, which are evidently designed to expose the larg- 

 est possible surface to the sunlight and the atmosphere. After 

 a few years of growth, a portion of its annual crop of buds 

 develop into blossoms, which in time become fruits with seeds. 

 Thus the chief end of all vegetable life, so far as the 

 plant itself is concerned, seems to be the perpetuation of the 

 species, — the multiplication of itself. But in the wise econ- 

 omy of nature no living thing exists for itself alone, and veg- 

 etation is the indispensable forerunner and companion of 

 animal existence. The air we breathe, our food, our clothing, 

 our timber, our fuel, our artificial light, and the mechanical 

 power, of our domestic animals, and our steam-engines, are all 

 the more or less direct results of vegetable growth. Now, 

 living lacings grow only by the digestion and assimilation of 

 food, and one of the first objects of inquiry for the botanist is, 

 "Upon what, and how do plants feed?" They are seen to 

 flourish as epiphytes without any connection with water or 

 soil ; they thrive most luxuriantly in the briny ocean, and they 

 spring out of the earth as if that were the great storehouse of 

 their existence. The careful investigations of modern science 

 have explained these mysteries and taught us what it con- 

 cerns every botanist and every farmer to know, and what, 

 thanks to Professor Johnson, they may now readily learn, 

 namely, " How Crops Grow," and "How Crops Feed." We 

 are also promised a volume, by the same learned author, 



