June 22, 1888.] 



SCIENTIFIC NE\VS. 



585 



INTELLIGENCE OF INSECTS. 



l\/rR. ROMANES, in a recent lecture at the Royal 

 Institution, pointed out the intellectual power dis- 

 played by insects ; they rank sometimes higher than 

 some mammalia in this respect. He had received a 

 communication from Mr. Langley, one of the first 

 astronomers in America, with reference to a spider 

 which had dropped a fly, that it had killed,'from the bar of 

 a window to the ground ; the fly was too heavy to be 

 lifted in an ordinary way, and the spider had to devise 

 some cunning method of doing it. Analogous to lifting 

 a fly, we may suppose ourselves to have to lift a heavy 

 ox up a high cliff with nothing at hand but unlimitable 

 rope ; how should we do it ? Mr. Romanes stated that he 

 had given aproblem to two senior wranglers, both of whom 

 failed to solve it. The spider's device, however, was 

 simple, like most inspirations of genius, and the follow- 

 ing diagram is an attempt to show its method of pro- 

 cedure, though it is difficult to demonstrate it clearly 

 without the aid of a blackboard on which to erase the 

 lines after the manner of the spider in proceeding with 



its work. Let AB represent the window bars from which 

 the fly has fallen, and B the place where the spider 

 wishes to deposit the fly. Let E, be the fly on the ground. 

 The spider walked as far as D, just above the fly, and 

 dropped a line, attaching the fly to it. Then it retired 

 to the position F, and dropped a guy-line GF ; next it 

 drew up the guy-line so as to draw the main line DE 

 into a loop as indicated by the dotted line, and fastened 

 the guy-line thus drawn up at F. Now it proceeded to 

 the point I, just above where the fly was in its altered 

 position, and again dropped a vertical line, and then 

 another guy-line from K to the new vertical line IE'. It 

 then hauled on the new guy, and fastened it at K, and 

 as soon as this was done it destroyed the lines DE and 

 FG, which were no longer of use. In this way the spider 

 continued to drop a series of vertical and guy-lines until, 

 and by degrees the fly was finally hoisted into the 

 required position. 



A New Species of Fish. — M. Victor Fatio (Coniples 

 Rmdus) has discovered a new species of fish in the 

 lake of Bourget. It belongs to the Sa/moiiidce. 



EXPERIMENTS IN CAPILLARY 

 ATTRACTION. 



FEW subjects arc so fertile in simple experiments, 

 requiring little or no special apparatus, as capillary 

 attraction. Faraday, who was unrivalled as a popular 

 lecturer, continually employed the simplest possible 

 method of illustrating the action of this subtle force. 

 One of the most striking he performed thus : A pile of 

 salt was placed upon a plate. The lecturer then poured 

 into the plate a saturated solution of salt in water. The 

 solution was coloured to make it easily visible. As it 

 was poured about the base of the salt, it was drawn up 

 throiigh the pores existing between the grains. By the 

 operation of capillary force the coloured solulion 

 gradually rose upwards, colouring the salt as it ascende 1. 

 The clue to the success of this experiment is in the 

 use of the salt solution instead of plain water. Were 

 the latter used, it would rapidly disintegrate the pile of 

 salt, by dissolving it. With the saturated solution the 

 solid salt is quite unaffected. 



In the illustration is shown a modification or develop- 

 ment of this experiment. The apparatus required is a 

 little more extensive, as, in addition to the plate, a glass 

 funnel and an india-rubber balloon are needed. 



The balloon should be inflated to its largest size, and 

 kept so for some time, so as to stretch the rubber well. 

 This is to enable it to fill at low pressure. The glass 

 funnel should be as large as possible, as the demonstra- 

 tion is more satisfactory when executed on a large scale. 



The funnel is filled with perfectly dried salt well 

 pulverised, which is pressed in as hard as possible. 

 The funnel is completely filled with it, when supported 

 mouth upward. The filling may be carried a little above 

 the rim. The plate is then placed over its mouth so as to 

 bear against the salt, and the whole is inverted. Tiie 

 object is to so conduct the operation that the salt shall 

 not settle down or change its position, but shall remain 

 in close contact with the wall of the funnel. All these 

 precautions are quite essential to success. 



The mouth of the balloon, whence the air has been 

 expelled, is now sprung over the open end of the funnel, 

 as shown in the cut. It is not necessary to tie it on 

 The balloon must, of course, be perfectly empty. 



The plate, funnel, and balloon are now ready for the 



