372 PHYSIOLOGY OF THE INVERTEBRATA. 



following : {(r) Certain moths formerly entered the hives of the 

 working-bee, and thereby caused great damage to the coniby 

 &c. To prevent this nuisance the bee built a barrier, which 

 now prevents the entrance of the larger intruders, yet at the 

 same time allows the entrance of the rightful owner. Qj) On 

 the authority of an American naturalist, a pastrycook in 

 Chicago found his shop invaded by a colony of ants, who 

 feasted nightly on the delicacies deposited on a certain shelf. 

 After cudgelling his brains for some time in order to discover 

 a plan for stopj^ing the depredations of the active insects, he 

 resolved to lay a streak of treacle around the tray containing 

 the coveted food. In due time the ants came forth in their 

 hundreds, and were led towards the feast by their chief. On 

 reaching the line scouts were then sent oxit to survey, and 

 eventually " the word of command " was passed around, and 

 instantly the main body of the ants made for a part of the 

 wall, where the plaster had been broken by a nail. Here 

 each snatched up a tiny piece of mortar and returned to the 

 spot indicated, where their burdens were deposited upon the 

 molasses. By this means, and after an infinite amount of 

 labour, a bridge was formed, and the triumphant army 

 marched forward to partake of the fruits of victory, the pastry- 

 cook meanwhile standing by filled with wonder, {c) The 

 dens or burrows of the trap-door spiders having been entered 

 by large predacious insects, these spiders constructed smaller 

 lateral burrows, provided with trap-doors, into which they 

 can now retreat in case the dens are forcibly entered. In 

 this way these spiders protect themselves against enemies. 

 {d) The modes of building webs across various streams ; the 

 strengthening of webs by buttress-like devices, when they 

 are constructed in gorge-like and windy situations : these 

 facts, combined with the power of the spider to adapt itself 

 to every possible circumstance, seem to point out that the 

 spider (as well as many other Invertebrates) is not guided 

 merely by " blind instinct," but by that which is the equiva- 



