430 proceedings of the academy op [1881. 



September 27. 

 The President, Dr. Ruschenberger, in the chair. 

 Eighteen persons present. 

 Dr. E. C. Hine was elected a membei". 



October 4. 

 Mr. J. H. Redfield, in the chair. 

 I^ineteen persons present. 



How Orh-Weaving Spiders make the Framework or Foxinda- 

 tions of Webs. — Rev. Dr. H. G. McCook said that he had given 

 attention during the past summer to tlie mode of constructing 

 webs prevailing among orb-weaving spiders. He had been led to 

 malie some special studies of the extent to wliicli air currents are 

 utilized in laying the foundation lines upon Avhich the orbs are 

 hung, by a remark of Rev. 0. Pickard-Cambridge in his work on 

 the Spiders of Dorset.^ " Spider lines," he says, " may frequently 

 be observed strained across open spaces of many feet and even 

 yards in extent. This has been explained by some naturalists to 

 have been done by the help of a current of air carrying the thread 

 across. I cannot, of course, say that it has never been thus 

 effected; though I have certainly never myself witnessed it. I 

 have, however, on several occasions seen a spider fix its line, then 

 run down to the ground, across the intervening space, and so up 

 the opposite side, trailing its line as it went ; and then having 

 hauled in the slack, it fixed the line to the desired spot. This, I 

 believe, to be the usual mode of proceeding in such cases." 



Dr. McCoolc was satisfied that on both the above points this 

 distinguished araneologist had failed to possess himself of all the 

 facts ; but he took up the points in question anew during the 

 summer, and made notes of his studies. His previous opinion 

 was fully confirmed. He had in a great number of cases 

 observed orb-weavers passing from point to point by means of 

 lines emitted from their spinnerets and entangled upon adjacent 

 foliage or other objects. These mimic " wire-bridges " were of 

 various lengths owing to the direction of the wind, and the rela- 

 tive positions of the spider and the standing objects ai'ound it. 

 Lines of two, three and four feet were frequent ; lines of from 

 seven to ten occurred pretty often ; he had measured one twenty- 

 six feet long, and in several cases had seen them strung entirely 



' Vol. i, Introduction, p. xxi. 



