QUERIES AND ANSWERS. 177 



inches in diameter and forty inclies deep, the smallest pots about ten 

 inches in diameter. Tlie station grounds occupy about three and a lialf 

 acres, and are so arranged that the pots are moved by tram cars in the 

 open air on days not raining, but kept under cover during inclement 

 weather. While the conditions of pot culture are not the same as in the 

 open field, it is nevertheless the most exact system of research into the 

 growth of plants, soil exhaustion and soil drainage, as the pots can be 

 brought under the control and protection of the experimenter, while in 

 the open field all sorts of complications arise. 



985. Q. What is the soil in relation to vegetation ? rpj^^ g^^^^ 

 A. It is both a laboratory and a mine. Certainly our own rich, black 



prairie soils are mines containing the vegetable accumulations of genera- 

 tions, but unfortunately by bad systems of cropping they are being ex- 

 hausted. Of course the soil is also a laboratory, for all applied manures 

 must pass through chemical changes and combinations effected to fit them 

 for food for plants. A very small portion of the commercial fertilizers 

 are, as applied to the soil, in a condition to be at once taken into plant 

 systems simply by being dissolved in water, they have to undergo more 

 or less change. If this were not so their action would be as quick and 

 transient as a flash of gunpowder, whereas they often take two or three 

 years to cease their activity. 



986. Q. I never can grow a crop of perfect ears of sugar corn, the soft Corn Grub. 

 grain always being badly cut by a grub in the husk. Can I prevent it? 



A. The moth lays its eggs on the ear when it is very small, and the 

 caterpillars are ready to enter the ear before it is half grown. Without a 

 trial in the case the writer would venture to suggest the enveloping of 

 the immature ear by bands of loose paper, or envelop them in loose paper 

 bags like grape growers envelop grape bunches, but it would be necessary 

 to permit the silk at the end of the ear to protrude, otherwise pollination 

 would not take place. This very exposure of the end of the ear might 

 defeat the effort to preserve it from the attacks of the grub, for it might 

 afford a fit resting place for a late flight of moths to deposit their eggs. 



987. Q. Are there insects beneficial to agriculture ? Beneficial 

 A. There are thousands assisting in the pollination of flowers, and insects. 



thousands of others destroying noxious species of insects. It is estimated 

 there are in the world twenty millions of species of insects, and it is cal- 

 culated that a million or more are advantageous to agriculture. About 

 ten thousand species of predaceous or parasitic insects are known in the 

 United States, but it will not do for the agriculturist to lay by and hope 

 for nature to send to his aid a flight of insectivorous insects to eat up 

 others, for the beneficial hosts are small in numbers as compared with the 

 injurious forms. The well-known snake feeder or dragon fly, so common 

 in Summer, is a showy representative of beneficial insects, as it lives upon 

 others, which it kills. 



988. Q. What are the names of twenty or thirty of the most common weeds. 



