THE SPINNING ORGANS. 51 



exterior spools of the spinning field are always bent a little towards the 

 centre.* The spider, of course, possesses the power of regulating the flow 

 of silk as to quautit}', and can graduate it from the most delicate gossamer 

 thread to the thickest blanket which is used for the rapid enswathment 

 of insects. She can also play upon the sjiecial glands as occasion requires, 

 and extrude the viscid substance which forms along the spiral lines of an 

 orbweb, or the variously colored silk u.sed in cocooniug. 



The field of comparative anatomy, and especially of histology, affords 

 innumerable examples of the wonderful beauty of structure and adapta- 

 tion of organs to the various uses of living creatures. But there are few 

 objects better calculated to awaken admiration, even to the point of en- 

 thusiasm, than the machinery by whicli the Orbweaver is enabled to 

 prosecute her spinningwork. 



• Meckel. 



