ANATOMY AND PHYSIOLOGY 



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conforms to the general segmentation and is arranged in each 

 segment with an approach to symmetry. Much of this tissue 

 forms a distinct peripheral layer in each segment, and masses 

 of fat-body occur constantly on each side of the alimentary 



Transverse section of the abdomen of a caterpillar, Pieris rapce. b, blood corpus- 

 cles; c, cuticula; d, dorsal vessel; f, fat-body; g, ganglion; h, hypodermis; /, leg; m, 

 muscle; mi, mid intestine, containing fragments of cabbage leaves; mt, Malpighian 

 tube; s, silk gland; sp, spiracle; tr, trachea. 



tract and also at the sides of the dorsal vessel, in the latter case 

 forming the pericardia! fat-body. 



Fat-Cells. The fat-cells (Fig. 164) are large and at first 

 more or less spherical, with a single nucleus (though there are 

 said to be two in Apis and several in Musca), but the cellular 



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