34 THE ROLL OF THE SEASONS 



vision seems miles away, then appears to float on 

 the retina as a hallucination, and at the end of a 

 second there is the viper just in front of the feet, 

 warning us not to step farther, beckoning us to come 

 and catch it. It is usually flung there in a careless 

 spiral, and looks like a whip-thong plaited in grey 

 and black, or sometimes yellow and black, with the 

 overlapping black parallelograms running down the 

 middle. 



Then, with mysterious suddenness, the viper 

 vanishes. It melts into the earth, if things are 

 what they seem, though reason tells us that it has 

 glided to its den, perhaps a yard away. There is 

 nothing more elusive when one watches a machine 

 than the polished thread of a twisting screw. It is 

 continually moving forward, yet remains in one 

 place. The spiral of the moving snake gives us the 

 opposite impression. The latter coils of it remain in 

 vision after they have i ,rnoved in substance. If you 

 wish to catch the tip of the tail, you must grasp at 

 the middle, and that with all the swiftness at your 

 command. And then, by placing your (preferably 

 harmless) snake in the middle of the field, you can 

 see how slow is its real progress by comparison with 

 the instantaneous way in which it vanishes in con- 

 ditions of its own choosing. 



It is far more often the female than the male viper 

 that we find thus carelessly flung out across the path 

 to catch the full force of the sun. It thus happens 

 that nearly all the illustrations in the natural history 

 books are taken from this sex, distended with eggs 

 and flattened out in the enjoyment of a maternal 

 sun-bath. That is the time when the most casual of 



