"Well, the aphids stay on the smart-weed roots until the corn is planted, which is in about ten days, and the kernels begin to germinate and to send down the tender juice-filled roots. And then the little brown ants take the aphids, now getting larger and stronger, of course, but still too helpless or stupid to do much for themselves except to suck sap, and carry them from the smart-weed roots to the corn-roots--What's that, Mary?" But Mary had said nothing; just drawn in her breath with a little sound. Still I think it best to remind her that I _do_ know Professor Forbes and that he really _does_ always tell the truth. In fact, I quote to Mary this honest professor's exact words about this transfer of the aphids from the weed-roots to the corn-roots. This is what he writes in his intensely interesting account of the whole life of these little insects: "In many cases in the field, we have found the young root aphis on sprouting weeds (especially pigeon-grass) which have been sought out by the ants before the leaves had shown above the ground; and, similarly, when the field is planted to corn, these ardent explorers will frequently discover the sprouting kernel in the earth, and mine along the starting stem and place the plant aphids upon it." "And the little brown ants do all this so as to get honey-dew from the aphids?" asks Mary. "Exactly," I reply. "The ants take such good care of the aphids not because they pity their helplessness or just want to be good, but because they know, by some instinct or reason, that these are the insects that, when they grow up, make honey-dew, which is the kind of food that ants seem to like better than any other. Indeed not only the little brown ants alone take care of the corn-root aphids to get honey-dew, but at least six other kinds of ants that live in the Illinois corn-fields do it. But the little brown ants are the most abundant and seem to give the aphids the best care." "It is exactly like keeping cows, isn't it," says Mary. "But they don't have to milk them." "Well," I reply, "I don't know what you would call it, but some other ants that take care of some other kinds of honey-dew insects seem to have to carry on a sort of milking performance to make them pour out their sweet liquid. The ants have to pat or rub them with their hairy little feelers; sort of tickle them to get them to squeeze out a little drop of honey-dew. The truth is, Mary, if I should tell you the really amazing things that ants do, you simply wouldn't believe me at all. But the next time we go out, I'll take you to see for yourself an ant community right on the campus that does some remarkable things. I'd much rather have you see the things yourself than tell you about them." "I'd rather, too," says Mary, which isn't exactly the nicest thing she could say, but I know what she means. It's that seeing is better than being told by anybody.