THEORIES RESPECTING ITS EMISSION. 221 



entitled to high respect and consideration. One of 

 these gentlemen, Mr. John Murray, says, — " The 

 aeronautic spider can propel its threads both horizon- 

 ally and vertically, and at all relative angles, in mo- 

 tionless air, and in an atmosphere agitated by M'inds; 

 nay, more, the aerial traveller can even dart its 

 thread, to use a nautical phrase, in the " wind's 

 eye." My opinion and observation are based upon 

 many Jiundred experiments. The entire phenomena 

 are electrical." * 



Mr. Blackwall, on the other hand, states, and I 

 concur in his opinion, that the glutinous matter 

 emitted from the abdomen is carried out into a line, 

 only in those situations where the insects are exposed 

 to a current of air. When a glass bell was placed 

 over them, they " remained seventeen days, evidently 

 unable to produce a single line by which they could 

 quit the branch they occupied, without encountering 

 the water" in which its base was immersed. f From 

 this, and many subsequent experiments, Mr. Black- 

 wall is " confident in affirming that, in motionless air, 

 spiders have not the power of darting their threads 

 even through the space of half an inch." + 



It is not a Uttle singular, that many very accurate 



* Insect, Architecture, p. 315. 

 t Linnean Transactions, vol. .\v. pt. ii. p. 456. 

 t Maa^azine of Natural History, vol. ii. p. 397. 



