Examination of the Spider. 39 



ested him ; their leaps upon their prey reminding 

 him of the tiger in pursuit of its victim. Over 

 every pathway in the forest he found a strong elastic 

 yellow web of a spider, allied to the Epeira clavipes^ 

 and note how carefully he examined them ! In 

 every web was found a small parasitic form, which 

 lived here undisturbed by its giant ally, feeding upon 

 the minute insects entrapped, — the crumbs from the 

 big spider's table. The young naturalist here ob- 

 served a remarkable instance of defence on the part 

 of a spider. As he approached, the little insect 

 imparted to its web a swinging movement, which 

 increased so rapidly that in a few moments the 

 cunning insect was invisible, or nearly so, from the 

 rapidity of its motions. This spider had a most 

 skilful method of disposing of its victims. The 

 moment a wasp or fly became entangled, the Epeira 

 held it at arm's length, and, in some miraculous way, 

 whirled it over and over, winding it up in a broad 

 band of threads, taken from its spinners, so that in a 

 few moments the captive appeared to be encased in 

 a cocoon, and then helpless was killed by the deadly 

 jaws of the monster. 



To show the virulence of the poison, Darwin 

 found that half a minute was sufficient to kill a large 

 wasp. 



On July 5, 1832, the Beagle left Rio, sailing 

 for the Plata. In the mouth of the latter he studied 

 the porpoise, watching its movements across the 

 bow as the vessel rushed along at full speed. Seals 

 and penguins were present in great numbers, and 

 were so demonstrative at night that the officer of 



