145 



made a nice little opening address to the children, the point 

 of which was to urge them to keep their eyes open, study 

 nature and see her plans in what she docs. Plants of differ- 

 ent species take the same elements from the same soil and 

 yet remain true to their nature and produce their own kind. 

 Up to a certain point plants must have the kind of food they 

 need; they, like animals, may absorb a small amount of 

 poison or injurious substance without apparent detriment, a 

 larger amount and suffer injury without dying, and still 

 more will kill them. Thus the speaker had put salt around 

 a pear tree until it rendered the pear unfit to eat, although 

 a fine looking fruit. The wants of a plant should be studied 

 the same as those of an animal, and it should be fed accord- 

 ingly. Very little progress was made in this direction for 

 two centuries after the landing of the pilgrims, and about 

 all that has been learned in the last fifty years is an appre- 

 ciation of our ignorance. The agricultural papers and far- 

 mers' institutes are doing much to throw light on dark 

 places. 



The chemist tells of what elements the plant is composed, 

 and one might naturally reason from that, that all there is 

 to do then is to feed into the land those elements. This is 

 not so. Clover contains more nitrogen than wheat, but it 

 will not do to feed the soil more nitrogen for clover than for 

 wheat. On the contrary, by some mysterious process 

 clover leaves more nitrogen in the soil than it takes from it. 

 Again, the elements wanted by plants may be plentiful in 

 the soil and yet hard to get at, while in other cases there 

 may be less of the same element in the soil, but in such a 

 form that it is readily obtainable. 



The elements of plant food are nitrogen, potash and phos- 

 phoric acid. Some soils may be rich in one or two of these 

 and deficient in others; it is the farmer's business to find 

 out just what his land contains and stands in need of, and 

 then to act accordingly. And this fact, and the method of 

 ascertaining it, was the one idea that Mr. Hersey made* 

 prominent in his lecture. 



