If one digs up with great care a root of alfalfa (it need not be an old plant, the youngest plant will show the same peculiarity), and care is taken in exposing the root (perhaps the best method is the washing away of the surrounding earth by water), some small nodules attached to the fine, hair-like roots are easily distinguished by the naked eye, and these nodules are the home of a teeming, microscopical, industrious population, who perform their allotted work with the silent, persistent energy so often displayed in Nature. Men of science have been able to identify at least three classes of these bacteria, and to ascertain the work accomplished by each. The reason for their existence would seem to be that one class is able to convert the nitrogen in the air into ammonia, whilst others work it into nitrite, and the third class so manipulate it as to form a nitrate which is capable of being used for plant food. Now, although one ton of alfalfa removes from the soil 50 lb. of nitrogen, yet that crop leaves the soil richer in nitrogen, because the alfalfa has encouraged the multiplication of those factories which convert some of the thousands of tons of nitrogen floating above the earth into substance suitable for food for plant life. As a dry fodder for cattle three tons of alfalfa contains as much nutrition as two tons of wheat. The cost of growing alfalfa greatly depends upon the situation of the land to be dealt with; also upon whether labour is plentiful or not; but, in order to give some idea of the advantage of growing this cattle food, we will imagine the intrinsic value of the undeveloped land to be £4,000, upon which, under existing conditions, it would be possible to keep 1,000 head of animals, whereas if this same land were under alfalfa 3,000 to 3,500 animals would be fattened thereon, and the land would have increased in value to £20,000 or £30,000.