APPENDIX. 151 



The apparent exceptions to this rule, in which the larger 

 doors have fewer layers than some of the smaller ones, may 

 probably be accounted for in the following manner. 



During the heavy rains and in times of drought flakes of 

 earth often become detached from the sloping banks, and 

 carry away the doors of such nests as are found in them. 



This happens frequently, and the spiders hasten to repair 

 the damage and spin new doors. 



But I have found, on examining eight of these new doors, 

 that, even in large nests,* they do not then contain more than 

 three layers of silk ; so that each time a nest of any size loses 

 its door, the number of layers is greatly reduced. 



In the case of six of these nests I had myself acted the 

 part of the landslip and removed the existing door. These 

 original and apparently undisturbed doors measured 3^, 4, 5, 

 5, 5, and 5 lines across, and contained respectively 5, 7, 8, 13, 

 9 and 5 layers of silk ; while of the equally large doors which 

 replaced them five contained three layers of silk only, and the 

 remaining nest but a single layer. 



* Of the eight doors in question the smallest measured 3 4 lines across, and 

 the largest 7 lines. 



