ANATOMY AND PHYSIOLOGY 





FIG. 165. Transverse section of the abdomen of a caterpillar, Pieris rapce. b, blood cor- 

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

 muscle; mi, mid intestine, containing fragments of cabbage leaves; ml, Malpighian tube; s, 

 silk gland; sp, spiracle; tr, trachea. 



which the metamorphosis takes place; the amount of fat increases as 

 the larva grows, and diminishes in the pupal stage, though some of it 

 lasts over to furnish nourishment for the 

 imago and its germ cells. The gradual 

 accumulation of uric acid and urates in 

 the fat-body indicates an excretory func- 

 tion, particularly in Collembola, which A 

 have no Malpighian tubes. The intimate PIG l66 ._ Fat . cells of a cater . 

 association between the ultimate tracheal pillar, Pieris. A, cells filled with 



r v jiir.Li-.ji- ij drops of fat; .B, cell freed of fat-drops, 



branches and the fat-body has led some showing nucleus. After KOLEE. 

 authorities to ascribe a respiratory func- 

 tion to the latter. A close relation of some sort exists also be- 

 tween the fat-system and the blood-system; fat-cells are found free 

 in the blood, and the blood corpuscles originate in the thorax and 



B 



