APPENDIX. 187 



lay the larva either 1120011 bibulous paper on the table, or 

 upon soft cotton cloth held in the left hand, and press the 

 extremity of the body with one finger, always with the in- 

 terposition of cloth or paper, so as to force out some of the 

 contents of the body; this process is continued from points 

 successively farther back, a slight addi- 

 tional portion of the contents of the body 

 being gently pressed out with each new 

 movement. Throughout all this process y^^ 4.-\vound 

 great care should be taken lest the skin wire for support- 

 should be abraded by too violent pressure, ^o^ ^^ ^^^^ ^^^' ^ 

 and lest any of the contents of the body 

 soil its exterior or become entangled in the hairs or spines; 

 to avoid the latter, the caterpillar should be frequently 

 removed to a clean part of the cloth. When a portion of 

 the intestinal tube itself becomes extruded, it should be 

 gripped with a pair of strong forceps, and, the head re- 

 maining in the secure hold of the left hand, the tube 

 should be forcibly but steadily torn from its attachments; 

 with this most of the contents of the body will be with- 

 drawn, and a delicate pressure passing with a rolling 

 motion from the head toward the tail will reduce the sub- 

 ject to a mere pellicle. 



The alcohol-lamp is now lighted and placed in position 

 beneath the oven; a wheat straw is selected, of the proper 

 size to enter the enlarged vent, and the tip, after being 

 cut diagonally with sharp scissors or a knife, is moistened 

 a little in the mouth (to prevent too great adhesion of the 

 skin to the straw) and carefully introduced into the open- 

 ing of the caterpillar; the process may be aided by blowing 

 gently through the straw. When the skin is slipped 

 upon all sides of the straw to the distance of about a fifth 

 of an inch, without any folding of the skin and so that 

 both the anal prolegs protrude, a short delicate pin (Edel- 

 ston and Williams, No. 19, is best) is passed through the 



