SPIDERS AND THEIR WAYS. 



•89 



tubes, having solid walls, and the end truncated with a mem- 

 branous surface, riddled with holes. By these microscopic open- 

 ings escapes the liquid which, hardened in contact with the air, 

 becomes the thread out of which the web and the cocoon are 

 made. Although it is cited as the 

 type of fineness, this thread is 

 formed of several fibers, which 

 adhere together on issuing from 

 the spinneret. It is unrivaled for 

 evenness, delicacy, and power of 

 resistance. 



The internal organization of 

 the spider is even more admira- 

 ble than the external parts. It 

 would be hardly possible even to 

 point out in this paper the most 

 essential features of it. It would 

 be going into long details to de- 

 scribe a muscular apparatus hav- 

 ing a power of which the animal 

 kingdom affords few examples, 

 assuring wonderful precision and 

 agility in movement ; a nervous 

 system whose enormous develop- 

 ment accounts for faculties of a 

 superior order ; and a stomach of 

 construction peculiarly adapted 

 to a diet composed exclusively of 

 fluids. It is written that spiders 

 breathe by lungs. They have an 

 aerial respiration, but it is by or- 

 gans very different in structure 

 from the lungs of man. They 

 consist of minute pockets containing flattetaed sacks packed like 

 the leaves of a book, through the walls of which the blood in- 

 filtrates, and the interior of which is penetrated by the air. 

 Thus observed under water, the little sacks appear like so many 

 sheets of silver communicating with the outside by slits at the 

 bottom of the belly. Spiders have also a heart and a cir- 

 culation of blood of the most complex character. The heart, 

 which is on the dorsal face, is of an ideal anatomical structure, 

 and long evaded the attempts of investigators to discover the ves- 

 sels that carry the blood to the periphery of the body. The main 

 vessels were finally traced out by means of colored injections in 

 the Euroj)ean species, and the smaller ones afterward in the larger 

 South American species. The study was a most charming one to 



Fig. 1. — Parts op a Spider, 



Under part of a spider's body— <, the thorax 

 or chest, from which the eight legs spring, 

 and to which the head is united in one 

 piece ; /, fangs ; /), palpi or feelers attached 

 to the jaws ; a, abdomen ; b, breathing 

 slita ; s, sis spinnerets, with thread com- 

 ing from them. 



Front of spider's head— «, eyes ; p, palpi ; I, 

 front legs ; h, hasp of fangs ; /, poison 

 fangs ; j, outer jaws. 



