Page:The American Cyclopædia (1879) Volume XV.djvu/500

 480 SUNDEW in wet sand along the coast, from Plymouth, Mass., to Florida; it has a bulb-like base or corm, from which rise the singular thread- like leaves, from 6 to 12, and sometimes 18 in. long, in which there is no distinction between blade and petiole, having the upper surface Leaf of Eound-Ieavod Sundew, viewed laterally. (Magni- fied four times.) somewhat convex ; the scapes, which are a lit- tle longer than the leaves, bear handsome rose- purple flowers more than half an inch across. It was long known in a general way that numerous small insects were caught by coming in contact with these viscid glands, and about 1860 it was discovered that this was not ac- cidental, but that the leaves were especially adapted to the work, and that though their motions are much slower than those of the re- lated dioncea, they are none the less effective, and the droseras now rank among the plants which catch and digest insects for their own nourishment. Darwin, in his recent work on ''Insectivorous Plants" (1875), gives in great detail the investigations of himself and others upon droseras and a few other genera, but two thirds of the work is devoted to drosera rotundifolia alone. The upper surface of the leaf is thickly studded with the glandular hairs already mentioned, to which Darwin gives the name of tentacles ; the average num- ber of these on 31 leaves was found to be 192; those on the central part of the leaf are short and erect, with green pedicels ; toward Konnd-leaved Sundew, seen from above. 1. Tentacles partly Inflected. 2. Tentacles entirely inflected. the margin they are larger, inclined outward, and have purple pedicels; those upon the extreme margin project on the same plane with the leaf, and are commonly reflexed, while a few which spring from the top of the petiole are the largest of all, some being i in. SUN FISH long ; each tentacle consists of a straight, hair- like pedicel or stalk, consisting of several rows of elongated cells filled with a purple fluid ; the gland at the apex is mostly oval and com- plex, and secretes a colorless and extremely viscid matter, which may be drawn out into long threads. If a small object, organic or inorganic, be placed on the centre of the leaf, the tentacles nearest it begin to bend toward it; this impulse is transmitted to those fur- ther off, until all, including the marginal ones, are closely inflected over the object, a process requiring from one to four or five hours. In case an insect alights upon or touches one of these glands, it is held by the secretion, and in its struggles comes in contact with other glands, which hold it until the tentacles can fold over it one by one and completely im- prison it. The insects thus caught are actually digested, and the nutritive material absorbed to contribute to the growth of the plant ; it is found that the secretion from these glands or Thread-leaved Sundew (Drosera filifermis). tentacles has a digestive power closely resem- bling that of the gastric juice of animals, act- ing even upon cartilage and the fibrous sub- stance of bone. Experiments with several other species of drosera show that, though the leaves vary greatly in shape and appearance from those of D. rotundifolia, they differ but little in their functions. Some of the curious results obtained by Mrs. Treat with our thread- leaved sundew are given in the article INSEC- TIVOROUS PLANTS. SUN FISH, the common name of the fish- es of the diodon family and genus orthago- riscus (Schn.). The skeleton is soft and only partially ossified ; the body short and round, compressed laterally ; the skin rough, covered with mucus, but without spines; jaws undi- vided in the middle, forming a cutting edge ; mouth small, the teeth adapted for bruising sea weeds and soft-bodied animals ; the body is truncated posteriorly, looking as if it had