THE BUTTERFLY. 



167 



ing the body with a little oil. We know, from the 

 bending and stretching of the caterpillar's body, that 

 he must have good muscles. Caterpillars can throw 

 themselves straight out from the limb of a tree, as you 

 throw out your arms from your body, and keep in 

 that position without moving for an hour at a time. 

 This shows how very strong the muscles must be, and 

 they are also very numerous. Some caterpillars have 

 over four thousand separate muscles! They are far 

 more curious than the lobster's, because, besides the 

 blood-vessels and nerves which pass through them, 

 they are all tunneled by the ringed tubes, or trachea. 

 There are two other large parts, or organs, in the cater- 

 pillar, which, if you did not know better, you might 

 take for the stomach and intestine. They lie on 

 either side of the digestive organs, and look like a 

 large intestine, a good deal twisted, and tapering to 

 a fine thread at each end (Fig. 136). This tube is filled 

 with a soft, toughish glue, or gum, which seems to 

 come from the food through one of the fine threads, 

 the one that opens into the digestive canal. The 

 other thread opens into the mouth by a tiny tube (Fig. 

 136), called a spinneret, or little spinner. Now, what 

 is it that our caterpillar has to spin ? Why should he 

 be a spinner as well as a tailor ? You have often seen 

 the caterpillar swinging by a thread. He can let him- 



