HABITATIONS OF INSECTS. 



399 



of giving information to the spider of what is passing above. 

 You doubtless suppose that in saying door, I am speaking 

 metaphorically. It could never enter into your conception 

 that any animal, much less an insect, could construct any 

 thing really deserving of that name — any thing like our 

 doors, turning upon a hinge, and accurately fitted to the 

 frame of the opening which it is intended to close. Yet 

 such a door, incredible as it may seem, is actually framed by 

 this spider. It does not, indeed, like us, compose it of wood, 

 but of several coats of dried earth fastened to each other with 

 silk. When finished, its outline is as perfectly circular as if 

 traced with compasses ; the inferior surface is convex and 

 smooth, the superior flat and rough, and so like the adjoining 

 earth as not to be distinguishable from it. This door the 

 ingenious artist fixes to the entrance of her gallery by a 

 hinge of silk, which plays with the greatest freedom, and 

 allows it to be opened and shut with ease ; and, as if ac- 

 quainted with the laws of gravity, she invariably fixes the 

 hinge at the highest side of the opening, so that the door 

 when pushed up shuts again by its own weight. She has 

 not less sagaciously left a little edge or groove just within 

 the entrance, upon which the door closes, and to which it fits 

 with such precision that it seems to make but one surface 

 with it. Such is the astonishing structure of this little 

 animal's abode ; nor is its defence of its subterraneous cavern 

 less surprising. If an observer adroitly insinuates the point 

 of a pin under the edge of the door, and elevates it a little, 

 he immediately perceives a very strong resistance. What is 

 its cause? The spider, warned by the vibrations of the 

 threads which extend from the door to the bottom of her 

 gallery, runs with all speed to the door, fastens its legs to it 

 on one side, and on the other to the walls, and, turning upon 

 its back, pulls with all its might. Thus the door is alter- 

 nately shut or opened, as the exertions of the observer or of 

 the spider prevail. It is easy to guess which will in the end 

 conquer; and the spider, when it finds all resistance in- 

 effectual, betakes itself to flight, and retreats. If, to make a 

 further experiment, the observer fastens down the door so 

 that it cannot be forced open, the next morning he will find 



