STRENGTH OF WEBS AND POWER OF SPIDERS, 



239 



where it shows as a tissue of close texture. Tn the building of additions 

 to the web, however, the new part shows as a quite open plane of 

 mesh work.^ 



The webs of Medicinalis are often built in the angles of cellar 



windows, along the sill, and in positions quite similar to that in which 



the Batavia snake was caught. The strength of several snares, 



-rnr^-^ fouud lu tlic cclkirs of the Academy of Natural Sciences of 



Piiiladelphia, was tested as follows : two webs bore up under 



a pencil weighing sixty-eight grains ; several small webs bore a weight 



of one-fourth and one-half ounce in corks spread over the surface, but 



Fig. 221. The pouch, web, tower, and cocoon of the Medicinal spider, Tegenaria medicinalis. 



broke down under an equal weight condensed into a small shell. One 

 web bore up easily, and apparently would have carried for an indeti- 

 nite period, the half ounce shell. It also .sustained for a short period 

 a weight of one ounce, and then gradually gave way by the breaking 

 down of the thread attachments to the wall, without any yielding of 

 the sheet itself. 



The weiglit of a " striped snake," such as is alhided to, jn-obably 

 our common garter snake, Eutu3nia sirtalis, Linn., is accurately fifty-five 



' The two we})s (Fig. 221) nioa.siired : N(i. 1 (uppor), 14 inches long across the hyjjothe- 

 nuse, by 10 im-hes deep; No. 2 (lower), IS inches long across the sheeted i)art, 24 inches 

 across the meshed extension, de])th i) inches. 



