HOW TO INFLATE A CATERPILLAR 55 



alimentary canal, but without cutting the common duct. Draw 

 them and make a diagram of the nerve-cord, showing the 

 segments in which each ganglion lies. 



Examine the tracheal system more fully. Observe the 

 longitudinal trunks, the short and rather wide branches which 

 lead into it from the spiracles, and the branches of distribution, 

 segmentally arranged. Cut out a piece of a large trachea, and 

 examine it under the microscope. Observe the spiral thicken- 

 ing and the mode of branching. 



13. (PRACTICAL.) HOW TO INFLATE A 

 CATBRPILLAE, AND SET A MOTH 



Dried caterpillars inflated with air, so as to retain something 

 hke their natural shape, are very useful additions to the 

 cabinet of Lepidoptera, and everyone who intends to study and 

 compare the various stages of injurious insects should know 

 how to make such preparations. 



The rough idea of the process is this. The empty skin 

 of a fresh caterpillar, when distended with air, takes the shape 

 of the living caterpillar. If it can be dried in this condition 

 it will form a tolerable model of the natural object, nearly 

 perfect in colour (unless the caterpillar is green) and surface- 

 marking. 



It is necessary first of all to empty the skin very completely, 

 and this can easily be managed after one or two attempts. 

 Kill the larva by placing it in a box with a few drops of ether. 

 Then lay it in the natural position on a sheet of blotting- 

 paper. Double the paper over the larva, and press gently 

 through the paper on the back, beginning at the head and 

 proceeding towards the tail. Before pressure is actually 

 applied clear the anus with a pin, so as to make sure that 

 the remains of the food can pass out. The pressure should 

 be applied steadily and continuously, and nothing answers 

 so well as the thumb. Begin by pressing the head of the 

 larva with the middle part of the thumb, and end by pressing 

 its tail with the tip of the thumb. The paper is kept between 

 the thumb and the larva all the time. A steady pressure, 

 brought to bear on every part of the body in succession, 

 forces out nearly all the contents through the anus. If the 



