Page:The history of silk, cotton, linen, wool, and other fibrous substances 2.djvu/145

 of animal, silky, and excremental particles; this forms the state of the growing caterpillar: in the next stage it is composed of animal and silky particles; it is then the mature caterpillar: and lastly, it is reduced to the animal particles alone; and is termed in this state the chrysalis. The poet Cowper, in the following lines, beautifully illustrates this subject:

The beams of April, ere it goes, A worm, scarce visible, disclose; All winter long content to dwell The tenant of his native shell. The same prolific season gives The sustenance by which he lives, The mulberry leaf, a simple store, That serves him—till he needs no more! For, his dimensions once complete, Thenceforth none ever sees him eat; Though till his growing time be past Scarce ever is he seen to fast. That hour arrived, his work begins. He spins and weaves, and weaves and spins; Till circle upon circle, wound Careless around him and around, Conceals him with a veil though slight, Impervious to the keenest sight. Thus self-inclosed, as in a cask, At length he finishes his task: And, though a worm when he was lost, Or caterpillar at the most, When next we see him, wings he wears, And in papilio pomp appears; Becomes oviparous; supplies With future worms and future flies The next ensuing year—and dies! Well were it for the world if all Who creep about this earthly ball, Though shorter-lived than most he be, Were useful in their kind as he.

It has been already noticed that the progressions of the insects are accelerated by an increase of temperature; and some variation will equally be experienced where different modes of treatment are followed; and, in particular, where different periods of the year are chosen in which to produce and rear the worm. Malpighius, in his "Anatomy of the Silk-worm," says,