Mr. J, Blackwall's Observatioiis on the House-Spider. 97 



property of forming for itself a reservoir of air, by means of 

 which it is preserved under water, is somewhat analogous to the 

 interesting habit of the Argyroneta, although it serves for a dif- 

 ferent purpose. In the present case, it is doubtless intended 

 to enable the animal to cross the water with safety." — T.B. 



Notwithstanding the boldness of the author's assertion, that 

 the spider, in the experiment cited above, made its escape 

 " by suffering a thread to be wafted to the edge of the glass," 

 it is apparent from his employing the phrase, " as was antici- 

 pated," that he had previously received a bias which disquali- 

 fied him for giving an impartial opinion in a case so defective 

 in evidence as the one under consideration. I say so defective 

 in evidence, because it may be fairly presumed that the escape 

 of the spider was Jiot witnessed by the experimenter, who even 

 admits the possibility of the animal having derived assistance 

 from the watei', in consequence of its being nearly on a level 

 with the top of the glass. Now the only manner in which the 

 spider could accomplish its purpose by means of the water 

 would be by traversing its surface; and that it actually did 

 so can scarcely be doubted, — for we are informed that when 

 some of the water was poured awaj', its plan of operations was 

 speedily changed, and every attempt made to regain its liberty 

 proved unavailing. 



Additional weight is given to this conclusion by facts which 

 have fallen under my own observation. Vai'ious kinds of spi- 

 ders are known to run upon water with greater facility than 

 they do on land ; and though the larger of our indigenous 

 species, including the Aranea doinestica, are, at least when 

 they have attained their full growth, incapable of doing so, 

 still they sometimes contrive to elFect a passage over its sur- 

 face by the following ingenious expedient. Placed on a twig 

 insulated by water they attach a line to it, which they seize 

 with the foot of one of the hind legs, allowing it to run freely 

 through the claws as it proceeds from the spinners. De- 

 scending to the surface of the liquid they use their best en- 

 deavours to pass over it; and should a little dust or other ex- 

 traneous matter happen to rest upon it, enabling them to ob- 

 tain even a slight footing, their efforts are frequently crowned 

 with success; the line, which chiefly contributes to support 

 them during their progress, and also serves to secure a return 

 to the twig, should their attempts prove abortive, being ulti- 

 mately made fast to the edge of the vessel containing the water. 

 It is most probable, therelbre, that the line which our author 

 affirms was wafted to the edge of the glass, had been conveyed 

 to it in the manner just described. 



When spiders descend beneath the surface of water, a bubble 

 Third Series. Vol. 1. No. 2. Aus: 1832. O 



