ANIMAL LIFE AND THE MICROSCOPE 



enlighten us concerning the uses of these combs. 

 At this point we may remark that the examination 

 of living creatures beneath the microscope should, 

 whenever possible, go hand in hand with a study of 

 habits. Over and over again in our microscopical 

 investigations we shall come across structures which 

 appear to be useless as far as we can surmise. A 

 careful observation of the living owners of these 

 puzzling structures will probably clear up the whole 

 matter. Well, let us watch a garden spider; if we 

 do so intelligently we shall see two uses of these 

 combs and may guess the third. The spider uses 

 its combs as we do, to straighten its hair; they also 

 clean its body. It uses them to obtain a firm grasp 

 of the threads of which its web is composed and, 

 though we cannot see this, so quick are the move- 

 ments of the creature, the combs serve a very useful 

 purpose in holding captured prey. 



The garden spider and its relatives are distin- 

 guished by the fact that, in addition to the two 

 large comb-like claws, they possess a third smaller 

 claw and some toothed spines. The small claw and 

 toothed spines are movable and, when pressed against 

 the combs of the larger claws afford their owner a 

 very firm grasp. With these cleverly contrived feet 

 she — it is always the lady spider who makes the 

 web and does all the work — hauls in the slack of 

 her web and owing to their firm grasp she can run 

 readily over its meshes. 

 The house spider, which spins a web seemingly in 

 disordered tangle and quite unlike the beautiful 

 113 H 



