LIFE AMONGST THE SPIDERS. 101 



brings the image in. contact with the rest. It is not a 

 little remarkable that the disposition of spiders' eyes is 

 exactly proportioned to their several habits ; so that in 

 no sense have they been acquired according to the theory 

 of evolution. 



Now fancy I am showing you the eyes of the large 

 jumping spider, scientifically known as Salticus tardi- 

 gradus, retaining their natural form and brilliant colour. 

 You see they are prepared without pressure, in glycerine, 

 and give you all the appearance of life, being mounted in 

 a deep cell, which contains the whole head of the spider. 

 Did you ever see such eyes! Why, they shine like so 

 many globes of pure opal ! Observe the combination of 

 optic mechanism for the perfection of vision, the arched 

 cornea and spherical lens, its concave-convex body, and 

 cup-shaped retina, with its layer of pigment. "How 

 wonderful!" you say. Truly so. These shining hemi- 

 spheres, we are told, are, in each case, covered with a thick 

 cornea, a continuation of the skin, which is perfectly 

 transparent, and thrown off in the process of moulting ; 

 for I must tell you that as spiders increase in bulk their 

 outer garments do not increase with their inner growth, 

 and they throw them off as exuviaB. I shall show you 

 presently one of these cast-off coverings, exhibiting the 

 entire outside form of the spider just before it would have 

 appeared in its new dress. But to think of these beau- 

 tiful eyes ! Let us take one more striking than the rest, 

 and, following the admirable description of a reliable 

 author,* very carefully observe the wisdom of God dis- 

 played in this act of creation. 



The centre of its inner surface is deeply excavated 

 for the reception of a crystalline lens, which, you will 

 observe, is globular in form, and which rests behind on 



* The late P. H. Gosse, F.R.S. 



