Jan. 1, 1866.] 



SCIENCE-GOSSIP. 



THE HOUSE SPIDER. 



SPIDERS are not now ranked among insects ; 

 because, as the handbooks of entomology state, 

 "they have no antennae, no division between the 

 head and the thorax ; they breathe by leaf-shaped 

 gills situated under the belly instead of spiracles in 

 the sides ; have a heart connected with these ; have 

 eight legs instead of six, and six or eight fixed eyes. 



With the exception of the dragon-fly, whose head 

 is terribly armed, there is not, perhaps, another 

 creature possessed of such a fearful array of weapons 

 as the spider. These weapons form beautiful micro- 

 scopic objects, and as such they deserve attention. 



The house spider (Aranea domestica) has eight 

 simple eyes ; these are set in two rows in the upper 

 part of the head, and beneath them are the two larger 

 jaws or mandibles ; each of these mandibles contains 

 a number of teeth, and is terminated by a large claw, 

 a portion of the inner side of which is finely serrated. 

 The number of teeth in a mandible is perhaps 

 variable : there are eight in the specimens from which 

 the figure given in this paper has been taken (fig. 2), 

 but sometimes five only have been found. The claws 

 frequently vary somewhat in the curvature of their 

 ends, and are more finely pointed in some instances 

 than in others. 



I have read somewhere that the action of these 

 claws is downward : this I have not been able to 

 verify, for in the cases in which I have seen them in 

 action, they were nearly horizontal, having only a 

 slight inclination downward; and in the cast skins 



of hair is perhaps used to clean the teeth of the op- 

 posite maxilla. 



^PPB 



Fig. 2. Mandible of Spider. 



to be found on old walls, the claws lie close to the 

 mandibles, and in a horizontal direction. Beneath 

 the mandibles are the maxillae (fig. 3), or smaller 

 jaws, each of these contains a row of very fine teeth, 

 and at the end of each row there is a thick tuft of 

 hair. The teeth are so placed that in all probability 

 the two rows work against each other, aud each tuft 



Fig. 3. Maxillae of Spider. 



With the assistance of an ordinary pocket magnify- 

 ing glass the action of the mandibles may be dis- 

 tinctly seen. It is a curious thing to watch a spider 

 making a repast of a fly ; to see with what dexterity 

 it uses each mandible alternately, as, with the 

 greatest ease, it turns the body of the fly round, and 

 presses it until it becomes a shapeless mass of juicy 

 pulp. 



The mandibles contain the poison, and the poison 

 duct may be traced to the extremity of the claw, if 

 the latter be sufficiently bleached before mounting. 



The rapidity and fatality of the action of the 

 poison has frequently been a subject of remark; the 

 following simple observation sets it in a clear light. 

 A stout fly became entangled in the web of a spider : 

 quick as lightning, out darts the spider and seizes 

 the fly, and equally quick was the interference to the 

 rescue; it was relieved and set at liberty, the fly 

 then walked smartly up a window-pane, stopped a- 

 while, brushed its wings with its hind feet, rubbed 

 its feet, and dressed itself ; this was the action of a 

 minute. It then walked about again, apparently all 

 right. Presently it stood without motion, and after 

 a few seconds, when touched, it was found to be 

 scarcely able to raise its feet, and after a few seconds 

 more it was quite dead. 



Much interesting matter relative to insects may 

 easily be obtained by the exercise of a little patient 

 and continued observation. The above has been 

 written with the desire of calling the attention of the 

 general reader to a few of the wonderful things in 

 the common objects of nature, and pointing out to 

 the young microscopist two objects easily found 

 upon which the first efforts at mounting may be 

 successfully exercised. 



Lewis G. Mills, LL.B., Armagh. 



