ARTICULATA. ]27 



the former by a small peduncle. The mandibles are strong, they move 

 vertically, or to some extent horizontally, and they have a terminal mo\-able 

 curved nail or tooth, which has a pore near the point through which a 

 poisonous fluid escapes. The mandibles of the male are generally larger 

 than in the female, although the individuals of the latter sex are usually 

 the largest. The palpi have live articulations, and are attached to the 

 raaxillse or jaws. They are pediform, simple, and ending with a nail in the 

 female, and variously shaped in the male. The maxillse vary much in 

 shape, and afford good characters in classification. Between the maxillae is 

 the labium or under lip. The feet are of the same shape, but differ in length 

 and thickness. They are usually terminated by a pair of serrated nails. 

 There are six or eight eyes, but generally the latter number, and they are 

 variously grouped in the different genera. The abdomen is usually soft, 

 and sometimes very large. The generative organs are situated at its 

 base beneath ; it contains two or four spiracles, and towards the extremity 

 are the vent, and spinnerets connected with the organs which secrete the 

 silk. 



The effect of the poison of spiders has been much exaggerated, although 

 under certain circumstances it may be serious. AValcknaer, a volumi- 

 nous writer upon these animals, states that he has caused himself to be 

 bitten by various species, but no ill effects resulted. 



Each spinneret of a spider contains a multitude of pores which, in some 

 sjDecies, amount to more than a thousand, so that the compound thread from 

 four spinnerets may contain four thousand strands. It has been suggested, 

 that as the strength of a rope is increased by being composed of many 

 separate strands, the strength of the cord of a spider is secured in the same 

 manner; but this is an error. The strands of a rope increase its strengtlx 

 because the ends of the separate short fibres are thereby better secured ; but 

 the silk of the spider, being a uniform fibre, cannot be compared with a 

 compound rope, and at best it is generally comparatively weak. The silk 

 being in a liquid state within the body, and much l)eing required in a short 

 time (as when the spider descends by its thread), the extreme tenuity of the 

 strands enables them to harden almost instantly by contact with the air. 

 ISTewly born spiders are cajjable of spinning, and Leuwenhoeck has calculated 

 that it would require four millions of the strands of one of them to form a 

 thread as thick as a hair of his beard. 



Some spiders shoot out long lines of silk, which have sufficient buoyancy 

 to ser^'e them as balloons for transporting themselves through the air. In 

 the autumn, these gossamers are abundant in the air and on the ground, 

 and they may be frequently seen floating in the breeze with a S])ider 

 attached. Thus an individual has been observed coming across the River 

 Susquehanna upwards of three hundred feet above the water towards a cliff 

 of that height. 



The webs of spiders are made according to various patterns. Some are 

 closely woven into a funnel into which the spider retreats, and opening 

 externally into a wide surface. The tube of the funnel sometimes extends 

 into a hole in the earth, or other material. Among the webs stretched to 



331 



