For years mankind has tacitly accepted the idea that fertilizing must be done, in plain anglo-saxon, with filth — animal, bird or human excrement, rotten bones, sewage, rotten anything, reinforced, to be sure, with such chemical matter as nitre, super-phos phates, lime, etc. Yet every one knows that despite all such matter put on the earth, the land is slowly but surely losing its fertility that insect pests increase, and, what is not so well known, the quality of the earth's pro ducts is deteriorating. Hensel saw what some day all the world will see, that plants require healthy food in order to ?ourish as much as man or beast does, and that sewage, etc., was not a healthy food.