Page:The New International Encyclopædia 1st ed. v. 06.djvu/495

* DRAGON-FISH. 427 DRAGONS BLOOD. less. A common Indian species is Pegasus draco, and another species {Pegasus voleiis) is frequently seen dried as a curiosity or serving as an ornament on boxes, etc., made in China. Lit- tle is kiiciwn of their habits. DRAGON-FLY. Any amphibious insect of the order t)donata. These insects possess nu- merous popular names, such as snake-feeder, horse-stinoer, spindle, devil's darning-needle, and mos(]uito-liavk. They lune very large heads. due to the excessive size of the eyes : the anteu- nse are short and the biting mouth-parts are pow- erful : the four wings are of similar size and structure; the legs are long and used for |)crch- ing rather than for crawling. Two distinct types of dragon-tlies are now recognized : ( 1 ) Zygop- tera, whose wings, in repose, are held upright: and (2) Anisoptera. whose wings are held hori- zontal. To the former group belong our conmion slender-bodied blue forms sometimes called damsel-rties. while to the latter l>elong our larger and usually more sombre species. Both kinds are most frequently found about ponds, marshes, or streams, but some forms go a considerable dis- tance from water, in meadows, in sumiy hours, where they hawk for small insects with exceeding speed and voracity. The Zygoptera fly nearer the ground and more among vegetation than do the Anisoptera. Dragon-flies are known to swarm, both in America and in Europe, but the causes of these migrations are luiknown. Although harm- less, these insects are much feared by persons un- acquainted with them, which explains some of the strange names and accounts for the quaint beliefs that exist among the country people, who say that if a "darning-needle' gets into your hair most disagreeable things will happen, the least of which is the sewing up of the ears. The folk-lore of Europe, the Orient, and .Japan abounds in superstitions and sayings in regard to these quite innocent but fierce-looking insects. The reproductive habits of dragon-fies are unique, in that there is no direct transference of the sperm from the genital ducts to the female, as in other insects. The sperm, previous to the transference, is stored in an accessory receptacle near the base of the male abdomen. The clasping attitudes are also peculiar. The male grasps the neck of the female by means of a pair of forceps at the end of the abdomen, the female then bends forward the apex of her abdomen to the accessory sperm-receptacle near the base of the male's ab- domen, and thus the actual transference of the sperm takes place. Among the Zygoptera the pairs often fly about tandem-like, the male clasp- ing the neck of the female : and in some species the male may even retain his hold and accompany her when the female crawls beneath the surface to oviposit. The females which go beneath the surface are those which oviposit in the tissues of plants. In some dragon-flies the eggs are dropped or washed off of the abdomen by dipping it into the water or striking it upon the surface. Larvae of Odonata are called 'nymphs.' and are aquatic and carnivorous. The lower lip is greatly developed and forms a powerful grasp- ing organ. The zygopteran nymphs have three plate-like gills at the end of the abdomen, while in the anisopteran nymphs respiration takes place in the greatly modified posterior part of the intestine into which water is drawn, and may be expelled with force sufficient to aid in locomotion. In the zygopteran genera Euphaea and Aniso- VoL. VI. -28. pleura the nymphs also pos.sc.ss. in addition to the terminal gills, lateral abdominal gills. Certain kinds of nymphs show decided preferences for cer- tain habitats, some choosing standing water, others small stream.s, and still others rapid water. These preferences are as marked as in the ease of the particular places frequented by the adults. When a nymph is fully grown it crawls out of water and attaches itself, by means of its claws, to some support. The nymph-skin then splits along the top of the head and down the back, and through this rupture the imago escajies. At first the body and wings are limp and contracted, and only gradually expand to their full size: but the adult colors do not appear for several hours, or even days, after emergence. The duration of the life of the imago varies from about three to six weeks for many forms, but in the case of those few forms which liibernate the limit may even extend over six months. Miile the dragon-fly. on account of its preying upon small insects and mosquitoes, is considered beneficial, the nymphs, on the other hand, have been credited with destroying young fish in hatch- eries. While small insects "doubtless form the bulk of their food, the larger species do not hesi- tate to attack even wasps and butterflies. The greatest extremes in size are found among the slender-bodied Zygoptera. The smallest is a Javanese species (Agrioeneniis minima), whose abdomen is about half an inch long, and the larg- est is Megatoprepus cccrulatus. from Central America, whose abdomen is about four inches long. A very large anisopteran {Gynacantha plagiata). from Borneo and Simiatra. has an ab- domen nearly equal the latter in length. About 2000 sjiecies of Odonata are known, the most of which are from tropical countries: but about .300 species occur in Xorth America. Fossil dragon-flies, of which at least 75 s]>eeies have been described, appear first in the Lias, where they present already a considerable differ- entiation, the majority of subfamilies being rep- resented in the rocks of that period. In the Ju- rassic limestones of Solenhofen, Bavaria, occur numerous examples, m.ostly of extinct genera, that are often preserved in the finest manner, with the wings spread out. Dragon-flies are also found in all the Tertiary insect-bearing beds, and the larv;e and pupoe occur in great abundance at Oeningen. Germany. See Xei"Ropter.. See Daji.sel-Fly and Plate of Dbagox-Flie.s and D.M.'SEL-Fi.iEs. DRAGON LEECH. See Leech, DRAGON OF WANTLEY, The. A ballad, apparently a parody on the old romances, which appears in Percy's liclii/ues. The dragon, who lives in a well, is killed by the hero. Jlore of More Hall, clad in a suit of spiked armor. DRAGON'S BLOOD fso called on account of the colon, or GvM t>R.c,oy. An astringent res- inous substance obtained from several trees of dilTerent natural orders," growing in warm coun- tries. The greater part of the dragon's blood of commerce is produced by the Calamus draeo, growing in the East Indies, the resin being at- tached in the form of hard, brittle masses to the fruits of the tree. Two varieties of dragon's blood occvir in conuiierce. One variety is brought in the form of sticks of various sizes, the other in the form of cakes. The separation of the resin