370 The Life of the Spider 



rapidly- widening circles to the circumference. 

 It is merely a temporary construction, whereof 

 naught but the central part survives when the 

 Spider has set its limy meshes. The second 

 spiral, the essential part of the snare, proceeds, 

 on the contrary, in serried coils from the circum- 

 ference to the centre and is composed entirely 

 of viscous cross- threads. 



Here we have, following one after the other 

 merely by a sudden alteration of the machine, 

 two volutes of an entirely different order as 

 regards direction, the number of whorls and 

 intersection. Both of them are logarithmic 

 spirals. I see no mechanism of the legs, be 

 they long or short, that can account for this 

 alteration. 



Can it then be a premeditated design on 

 the part of the Epeira ? Can there be calcula- 

 tion, measurement of angles, gauging of the 

 parallel by means of the eye or otherwise ? I 

 am inclined to think that there is none of all 

 this, or at least nothing but an innate pro- 

 pensity, whose effects the animal is no more 

 able to control than the flower is able to control 

 the arrangement of its verticils. The Epeira 



