In view of the fact that these various minerals play an indispensable part in healthy metabolism it is imperative that a sufficiency of them should be supplied in proper proportion in our daily food.  It is imperative, if we desire to retain or to restore health to the body.

These mineral elements are to be found in the first instance in the earth, but they are of no use to the body in that form.  We cannot digest and assimilate inorganic matter no matter how finely it may be pulverized.  But plants can assimilate them from the earth and organize them in such form as to make them easily assimilable by animals and man.

If the soil on which our food is produced is itself deficient in some of these elements, our food must also lack them.  If, moreover, we cannot for any reason add the missing elements to the soil, we must supply them to the human system in the shape of prepared nutritive salts.  It is preferable, of course, that our food should contain all of the elements necessary for the proper nourishment of the body.

Thus we are forced to return to consideration of the soil.  It is an established fact that our fields were originally formed from decayed rock, and analysis shows that this primitive rock contains the same minerals as healthy blood.  But if our agriculturists are taught that stable manure and three or four other things are all that is necessary for the fertilization of their fields, where shall the other minerals essential to human metabolism come from?

What a man is, largely depends upon what he eats.  Hence man is very largely a product of the fields.  When the soil is denuded of any of the elements essential to plant and animal life, it must be properly fertilized.  Incomplete or improper fertilization can have but one result, to-wit, it will produce sickly vegetation, and this in turn must produce unhealthy cattle, and since man is dependent upon plant and animal life for his food a sickly race of human beings is the ultimate result.

Is not barrenness of the soil responsible for disease in potatoes, for San Jose scale, Phylloxera, and other similar phenomena.  The fields are manured profusely, it is true, but the very chemical elements which are not only essential to the development of wholesome plant tissue but which would also enable the plant to protect itself against parasites, are not used.  Every farmer has observed, for instance, that grass grown upon cow dung in pastures is not eaten by cows, oxen or sheep.  The instinct of the animals is correct.

In using the term incomplete fertilization, I mean supplying only potash, phosphoric acid and nitrogen, and possibly lime and sulphur, when the soil is denuded of several other elements.  No matter how rich a field may be made in these things if it lacks other elements healthy vegetation cannot be grown in it.