THE LIFE OF THE SPIDER 43 



tarantulas are fine performers and their molting activities have been 

 described a number of times. During the late summer they usually 

 show evidences of an impending change and refuse to accept food 

 for days or even weeks. The dorsum of the abdomen has by this 

 time usually been rubbed completely bare, as a result of the normal 

 scraping characteristic of these creatures; and because they have 

 worn their covering of hairs for a full year, their bodies are dull 

 and quite bleached as compared with their fresh condition. 



Tarantulas ordinarily have their quarters liberally covered with 

 silk, but on this occasion they spin an expansive, closely woven 

 sheet of silk, appropriately termed the molting bed, which requires 

 several hours of intensive work. On this soft cover the spider lies, 

 turned completely over on its back and with legs outstretched, the 

 front and hind ones with tarsi affixed to the silken bed. To all 

 appearances it is dead, but if one watches the prone figure closely, 

 occasional slight movements can be detected. After two or three 

 hours, the old skin splits along the sides of the carapace, and the 

 old shield comes loose from the new integument. Splitting continues 

 over the pedicel and the sides of the abdomen until the dorsum of 

 the whole spider is partially freed, the old skin adhering more or 

 less closely for some time. At this stage, the spider has changed its 

 position so that it is lying on one side, and it now begins the labori- 

 ous process of pulling the appendages from their old casings. The 

 spider extracts its chelicerae first, and then starts a series of rhythmi- 

 cal contractions which gradually bring to light the femora, patellae, 

 and successively the rest of the legs. The first legs and the palpi are 

 freed initially, then come the posterior legs. After about an 

 hour, the cephalothorax and the legs are completely freed; where- 

 upon the spider easily extracts the abdomen and moves away from 

 the cast skin. For three or four hours it lies on its back or side 

 while the new skin hardens; then it resumes its normal upright posi- 

 tion. The freshly cast skin of the tarantula is moist inside, and the 

 new cuticle also shows traces of moisture. The molting fluid be- 

 tween the old and the new skins perhaps aids the progress of the 

 molt by loosening the old skin. 



Essentially the same picture is presented in the molting of true 

 spiders. The sedentary spiders hang in their webs or in their re- 

 treats. Many of the vagrants spin a few threads in a favorable nook 

 and hang downward, their tarsi fixed in the silken lines and their 

 abdomen supported by a thread from the spinnerets. The cuticle 

 splits around the sides of the carapace and around the abdomen. 



