CATERPILLAR AND THE MOTH
is likely to be unable to accomplish its transformation, or it will produce a dwarfed or an imperfect adult. How THE CATERPILLAR BECOMES A ?IOTH A short rime before the caterpillar is ready to spin its cocoon, it ceases feeding. Its body, as we have just learned, contains now an abundance of energy-giving sub- stances stored in the cells of its fat tissue. When the work of constructing the cocoon is started, the alimentary canal is devoid of food material, the crop is contracted to a narrow cylinder, and the stomach is shrunken and flabby. The stomach, however, contains a mass of sort, orange- brown substance which, when examined under the micro- scope, is round to consist, hot of plant tissue, but of animal cdls; it is, in fact, the cellular lining of the caterpillar's stomach which bas already been cast off into the cavity of the stomach. The latter is now provided with a new cell wall. The shedding of the old stomach wall marks the first stage in the dismantling of the caterpillar; it is the beginning of the pupal metamorphosis which will convert the caterpillar into the moth. The new stomach wall will first digest and absorb the débris of the old, in order to conserve its proteid materials for the constructive work of the pupa, and it will then itself become transformed into the stomach of the moth. After the caterpillar bas shut itself into the cocoon, its life as a caterpillar is almost ended. Its external appear- ance is already much altered by the contraction of the body and the "loss of the hairy covering, and during the next three or four days a furt?er characteristic change of form takes place. As the body continues to shorten, the first three segments become crowded together; but the abdomen swells out, while the abdominal legs are re- tracted until they all but disappear. The creature is now (Fig. I59 B) onl.?" half the length of the active caterpillar (A), and it would scarcely be recognized as the same in- dividual that so recently spun itself into the cocoon. l "-93 ]
INSECTS
