Page:Popular Science Monthly Volume 49.djvu/706

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possible, however, to deduce even from these precise criterions anything but an approximate conclusion. Ferri points out frankly, in the brilliant treatise that precedes his study of comparative anthropometry, the difficulties of such classification. He insists, for example, that, besides craniological characteristics and the qualities inherent in the individual and the race, due regard must be had to psychological conditions.



THE story of the trap-setting and insect-eating plants is a more than twice-told tale. The pitcher-plant, which beguiles the hapless fly to his drowning in its vase-shaped leaves, baited on the outside with nectar-bearing glands, and filled with water; the Venus's flytrap, which shuts up on him and crushes him; the sundew (Drosera), which chokes him in a sticky secretion, are all known, at least by pictures and descriptions, to the tyro in botanic study. And we have learned that they all have good and sufficient reasons for thus dealing with the hapless flies. For "the plants grow," says Grant Allen, "in places where the marshy and water-logged soil is markedly wanting in nitrogen compounds. Insect-eating leaves are thus a device to supply the plant with nitrogen by means of the foliage, in circumstances where the roots prove powerless for the purpose."

The insect slaughter which they carry on has the same excuse as the animal slaughter of the abattoir. It is killing for food, and the insects which these plants catch are honestly eaten and digested. But in the infinite analogy of the vegetable world we find a curious parallel to killing for sport. There are a few native flowers which entrap insects simply and solely, it appears, for the deed's own sake. The prisoners serve no apparent use in the plant's economy, nor do their poor little corpses nourish the plant's life. A botanist who let his imagination run away with him might accuse the guileless-looking flowers of that savage joy in another creature's pain which drew our forefathers in crowds to the badger-drawings and bear-baitings of bygone times.

One of these flower tormentors is the spreading dogbane (Apocynum androsœmifolium), which is common all summer, along shady roadsides and around the borders of thickets, in the Northern and Eastern States. The plant is about three feet high, erect and branching. The flowers are nearly as large as single blossoms of the lily of the valley, "and are very beautiful," says Mrs. Dana, "if closely examined. The corolla is bell-shaped and cleft, at the