ELISHA MITCHELL SCIENTIFIC SOCIETY. 21 



opportunity ©f observing the manner of enlargement of trap- 

 doors made by the spiders which he studied, or that he did 

 not offer some theory as an explanation. If the particles are 

 cemented to the edge, it would be quite natural that the spe- 

 cies of spider in my possession once made its door by first 

 spinning a web across the mouth of the tube, and then weav- 

 ing into it other material, as in the case of N. meridiortnlis; 

 and that the habits, followed through life and successive gen- 

 erations, of making additions to the door by cementing par- 

 ticles to the edge, finally became so fixed that this mode of 

 making additions to it became the permanent habit and type 

 of construction of the trap-door from the foundation ! The 

 rapidity, ease, and intelligence manifested in this method of 

 building up the door, piece by piece, certainly indicates a 

 higher development of instinctive power. A perfect and 

 neatly fitting and swinging door made in i y^ hours ! 



When I took the spider from her nest it was necessary to 

 remove nearly all of the soil from the jar and take her from 

 the lower end of the tube, as all efforts to attract her from the 

 nest failed. As the soil was very loose and the nest not 

 long made the walls of the tube collapsed. In ten days the 

 spider was returned to the nest. Though the trap-door was 

 capable of being used, and seemed to satisfy the spider's idea 

 of the " fitness of things," it was in a very dilapidated condi- 

 tion. This agrees wnth. what Mr. Moggridge says of the re- 

 luctance manifested by spiders to abandon an old nest. 

 The examples cited by him are that if a door be pinned 

 back, during the night a second door will be made ; that if 

 the nest be covered with earth the tube will be prolonged to 

 the surface of the superimposed earth and a new trap-door 

 will be made ; and that in some cases nests become inverted, 

 when, a door being made at the now upper end of the tube, 

 the nest will have a door at each end ! ' The conduct of my 

 spider under another condition farther illustrates this feature. 

 Wishing to observe the habit of the spider if possible while 

 the door of the nest was closed, I prepared a glass test tube, 

 jyiri.m. jj^ diameter by placing, 4*'"' from the mouth, a cork 

 bottom, so that the spider might have something on which 

 to stand while making the door. This, with the spider in it, 

 I placed in the glass jar and surrounded it with earth to 

 darken the walls, hoping thus, because of the firm smooth 

 surface of the tube she would not line it with silk, and by 



'Harvesting Ants and Trap-Door Spiders, pp. 121 and 122. 



