Page:Insects - Their Ways and Means of Living.djvu/361

 CATERPII.LAR AND THE MOTH

organs by means of enzymes produced in the nuclei of the cells. The fat cells thus take on the function of a stomach, converting the materials dissolved in the blood into forms that the growing tissues can assimilate. During this time the masses of fat tissue that compose the fat-body of the

"r<>:,.ç::o " :-:oE--: :¢.,' / e I. ,/"   é "... " "/""   O- " .- --.--..:»" :e«::.a«  <çi::.-:: O Fro. 6o. Bodies in the blood of a young pupa of the tent cterpillar a, a free fat cell, containing large oily fat globules, and small proteid granules; b, r, fat cells in dissolution; d, froe proteid granules in the bl?ed, and e, fat globules liberat from the disintegrating fat cells;f, bl?ed corpuscles

larva have broken up into free cells, and these cells, vacuolated with oii globules and later charged with pro- teid granules, now fill the blood. The interior of the moth pupa, or chrysalis, shortly after the larval skin is shed, contains a thick, yellow, creamy liquid. In it there may be discovered, however, the ali'mentary tract, the nervous system, and the tracheal tubes, the latter filled with air; but all these parts are so soft and delicate that they can scarcely be studied by ordinary methods of dissecion. The creamy pulp of the pupa's body, when examined under the microscope, is seen to consist of a clear, pale, amber-vellowish liquid full of small bodies of various sizes (.1Oig. 6o), which give it the opaque appearance and thick consistencv. The liquid medium is the blood, or body lymph. Tle largest bodies in it are free fat cells (a); sma'ller ones are probably blood corpuscles (f); and the

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