320 HOMES WITHOUT HANDS. 



rial from that of the viscid spiral line, which is elastic in an ex- 

 traordinary degree. Now the viscidity of this line may be shown 

 to depend entirely upon the globules with which it is studded; 

 for if they be removed by careful application of the finger, a fine 

 glossy filament remains, which is highly elastic, but perfectly un- 

 adhesive. As the globules, therefore, and the line on which they 

 are disposed, differ so essentially from each other and from the 

 radii, it is reasonable to infer that the physical constitution of 

 these several portions of the net must be dissimilar. 



"An estimate of the number of viscid globules distributed on 

 the elastic spiral line in a net of Epeira apoclisa of a medium size 

 will convey some idea of the elaborate operations performed by 

 the Epeira in the construction of their snares. The mean dis- 

 tance between two adjacent radii in a net of this species is about 

 seven tenths of an inch ; if, therefore, the number seven be multi- 

 plied by twenty, the mean number of viscid globules which occur 

 on one tenth of an inch of the elastic spiral line at the ordinary 

 degree of tension, the product will be 140, the mean number of 

 globules deposited on seven tenths of an inch of the elastic spiral 

 line. This product multiplied by twenty-four, the mean number 

 of circumvolutions described by the elastic spiral line, gives 3360, 

 the mean number of globules contained between two radii ; which, 

 multiplied by twenty-six, the mean number of radii, produces 

 87,360, the total number of viscid globules in a finished net of av- 

 erage dimensions. 



"A large net, fourteen or sixteen inches in diameter, will be 

 found by a similar calculation to contain upward of 120,000 vis- 

 cid globules, and yet Epeira apoclisa will complete its snare in 

 about forty minutes if it meet with no interruption." 



These calculations will serve to show the elaborate nature of 

 the webs which we see constantly in our gardens, as well as their 

 value to the architect. The secretion of the liquid from which 

 the lines proceed is a work of time, so that if a spider is forced to 

 spin several nets in rapid succession, it loses all its silk and can 

 not make a web. To wait until a fresh supply should be secreted 

 would be a terrible privation, and, moreover, the want of food 

 would stop the secretion, so that the spider has no other resource 

 than to make war on a weaker spider, drive him out of his net, 

 and usurp possession thereof. Such being the case, the spiders 

 are all very chary of using their silk, and never trouble them- 

 selves to make webs when a storm is impending. They are 



