THE SPIDER 



113 



silk are ; in the construction of cross-hairs in telescopes and, 

 in medicine, as a narcotic in case of fevers, — a temporary fad. 



Poisonous Spiders. — Spiders are feared by many people 

 from a belief that they are very poisonous, even fatally so. 

 Spiders have, indeed, biting jaws 

 provided with poison-glands, and 

 their bite is often fatal to insects 

 and even to small birds and mam- 

 mals. But most spiders cannot 

 spread the jaws sufficiently to make 

 a bite in the human skin, and even 

 the largest forms seem to inflict but 

 a slight wound, scarcely ever greater 

 than that of a mosquito. The 

 stories of the severe effects of the 

 bite of the Tarantula, one of the Ly- 

 cosidae, are entirely fabulous. 



Spiders show a marked sexual 

 dimorphism. Particularly among 

 the orb-weavers the males are much smaller than the females 

 of the same species, but the legs of the male are rela- 

 tively the longer and stronger. The male is usually shorter 

 lived than the female, for the latter has often to watch the 

 egg-cocoons, or carry them about with her until the 

 young hatch out. The male also builds less perfect webs than 

 the female. The relation existing between mated pairs is 

 often peculiar. The male is frequently killed and eaten by the 

 female ; but if the male can overcome the female she may 

 fall his victim. Among wandering spiders there is often a 

 selection by the female from among several rivals, which en- 

 gage in severe battles with each other. 



Fig. 114. — Ocyale (Pisaurina) 

 undata. Half grown, natural 

 size, resting on a screen door, 

 using it as a sort of artificial 

 web. Photo, by Emerton. 



