Uncle Paul drew down to the children’s level the top of a branch, and all looked at it attentively. Innumerable black velvety lice, immobile and so close together as to touch one another, cover the under side of the leaves and the still tender wood. With a sucker more delicate than a hair plunged into the bark, they fill themselves peacefully with the sap of the elder without changing their position. At the end of their back, they have two short and hollow hairs, two tubes from which, if you look attentively, you can see a little drop of sugary liquid escape from time to time. These black lice are called plant-lice. They are the ants’ cows. The two tubes are the udders, and the liquor which drips from their extremity is the milk. In the midst of the herd, on the herd, even, when the cattle are too close together, the famished ants come and go from one louse to another, watching for the delicious little drop. The one who sees it runs, drinks, enjoys it, and seems to say on raising its little head: Oh, how good, oh, how good it is! Then it goes on its way looking for another mouthful of milk. But plant-lice are stingy with their milk; they are not always disposed to let it run through their tubes. Then the ant, like a milkmaid ready to milk her cow, lavishes the most endearing caresses on the plant-louse. With its antennæ, that is to say, with its little delicate flexible horns, it gently pats the stomach and tickles the milk-tubes. The ant nearly always succeeds. What cannot gentleness accomplish! The plant-louse lets itself be conquered; a drop appears which is immediately licked up. Oh, how good, how good! As the little paunch is not full, the ant goes to other plant-lice trying the same caresses. [Illustration: Plant-louse] Uncle Paul let go the branch, which sprang back into its natural position. Milkmaids, cattle, and pasture were at once at the top of the elder bush. “That is wonderful, Uncle,” cried Claire. “Wonderful, my dear child. The elder is not the only bush that nourishes milk herds for the ants. Plant-lice can be found on many other forms of vegetation. Those on the rosebush and cabbage are green; on the elder, bean, poppy, nettle, willow, poplar, black; on the oak and thistle, bronze color; on the oleander and nut, yellow. All have the two tubes from which oozes the sugary liquor; all vie with one another in feasting the ants.” Claire and her uncle went in-doors. Emile and Jules, enraptured by what they had just seen, began to look for lice on other plants. In less than an hour they had found four different kinds, all receiving visits of no disinterested sort from the ants. ------------------------------------------------------------------------ CHAPTER V THE SHEEPFOLD