Marsh. 207 



serve a very similar protective purpose in many other cater- 

 pillars. 



But mark! the larva of the Puss moth is showing us 

 another of its peculiar methods of protecting itself. From 

 the two-pointed filaments into which the tail segment is 

 divided, two long pink flagella, or little whips, are being 

 thrust out and drawn back with great rapidity. Quite an 

 alarming appearance, you say. Indeed it is. The thrusting 

 out is called evagination, the drawing in, invagination, and 



FIG. 45. THE Puss MOTH (Dicranura vinula), MALE. 



we note that the flagella are withdrawn, as it were, into them- 

 selves, drawn in like a glove in process of being turned in- 

 side out, or a telescope that is being shut up. The tip 

 disappears first, and as the flagellum is drawn in, each part 

 from the apex to the base disappears in turn, until only a 

 tiny raised point shows where the base is. When evagina- 

 tion takes place, the basal part expands first and the apex is 

 the last to come from the inside. One of our very best natu- 

 ralists tells us that the power of contraction in the retractor 

 muscles of these organs is enormous. Many other caterpillars 

 have eversible glands, some of which give off irritant fluids, 



