Page:The American Cyclopædia (1879) Volume III.djvu/502

 496 BUTTERFLY changed into suctorial organs; the mandibles are very much reduced, and the maxilla? are transformed, each into a semi-canal, extensile, and capable of being rolled up spirally, which, when united, form the suctorial organ (lingua spiralis) ; at the base of this organ are two very short maxillary palpi, between which and the hairy labial palpi it is sheathed when rolled up ; this tongue, if it may be so called, is very long in the butterflies. In the caterpillar state these organs are masticatory and not suctorial, adapted for the food of these voracious larvee, while hi the perfect insect the long tongue is necessary to obtain the liquid honey contained in the deep calyxes of flowers. In some spe- cies the anterior and lateral surfaces of the niaxilliB are provided with a considerable num- ber of minute papilla?, which are probably organs of taste as well as of exquisite touch. The eyes are compound. The abdomen has six or seven segments, is attached to the thorax by a very small portion of its diameter, and has no sting nor ovipositor; the legs are six in number, each composed of five parts, the tarsus having five articulations; in some genera the anterior pair are short and folded against the chest, and entirely useless as locomotive organs. The ventral nervous system consists of seven ganglia, the first two, the largest, be- longing to the thorax; the connecting cords are single, except between the thoracic ganglia. In the caterpillars the ventral cord consists of 11 nearly equal ganglia; during the pupa state the first and second and the third and fourth are fused together, forming the second thoracic ganglia, which send off the nerves to the legs and wings ; the fifth and sixth are also fused into one. Respiration is effected by means of trachea? extending through all parts of the system, and opening externally by stigmata on the sides of the body ; the trunks arising from the stigmata open into two large lateral canals, from which the trachete branch off. They have a well marked urinary apparatus; the Malpighian or uriniferous tubes are usually six in number, long, free, and open into the stomach by two excretory ducts; the tubes contain cells, disposed in rows, filled with very fine granules of a dark or brownish color ; on the rupture of the cells, their contents pass into the stomach and digestive canal, and are either evacuated with the fseces, or separately as a troubled liquid; it is well known that they emit a considerable quantity of urine, when bursting from their pupa envelope. The two sexes are distinct, and the rudiments of the sexual organs exist in the youngest larvae, though their development takes place princi- pally during the pupa state. The females lay their eggs, which are numerous and vary in form according to the species, upon such vege- table substances as the larva? are to feed upon ; the time at which the eggs arrive at maturity coincides with the end of the pupa state, so that the sexes are ready to unite soon after they leave this state; this act accomplished, both sexes soon perish; the spermatic parti- cles are filiform and very active. The wings are membranous and veined, and covered with an immense number of beautiful scales, vary- ing in size, shape, and coloration, implanted by a small pedicle resembling the stem of a feather. An idea of the immense number and exceeding minuteness of these wing scales may be formed' from the fact that Leeuwenhoeck counted 400,000 on the small silkworm moth ; in a piece of modern mosaic work there may be nearly 900 separate pieces in an inch square, while the same extent of surface on a butter- fly's wing may contain from 100,000 to 900,- 000. The life of the butterfly is a continued series of changes from the time of its leaving the egg till it becomes a perfect insect. As soon as the caterpillar is hatched it begins to eat eagerly, and increases rapidly in size during this larva state, changing its skin several times ; before each change it ceases to eat, remains motionless, and sometimes attaches itself by a slight web to the under surface of a leaf; it gets rid of the old skin by various contractions of the whole body, which separate the dry and shrivelled covering on the back, the insect es- caping in the course of a few minutes ; some- times the internal lining of the alimentary canal, from the mouth to the extremity of the body, comes away with the skin ; the latter takes place most frequently when the larva is about to change into a pupa, and often proves fatal. When the full-grown caterpillar is ready to assume the pupa, nymph, or chrysalis state (for these are synonymous), it ceases to eat, evacuates the intestines, and suspends its contracted body to the under surface of some object, either by its legs, head downward, or by a little rope of silk ; after remaining sus- pended several hours, it changes its skin for the last time in the manner above alluded to ; the legs, antenna?, and wings are extended along the body, and the whole is strengthened by the drying of the transparent fluid which facilitated the separation of the skin. In the pupa state the insect does not eat, and remains perfectly quiet ; the pupa of the lepidoptera is said to be " obtected," because the future limbs are seen on the outside of the case. The duration of the butterfly in the pupa state de- pends much on external circumstances ; if this condition happen in the hot period of summer, the perfect insect may appear in eight or nine days, or it may be prolonged to two or three weeks, and may even exist during the whole winter ; during this state the insect is in a con- dition like that of the hibernating animals, res- piration and circulation being reduced to their minimum in the first part of its confinement, but becoming active toward the close. At the proper time the pupa case is burst open, and the perfect butterfly suspends itself with its new wings hanging downward ; after these have become developed fully by active respira- tion and circulation, the insect remains at rest a short time until the external covering be