ARCHlTECTUIiE OF MOTHS. 8? 



dimensions of its abode, by cutting it asunder in a 

 longitudinal direction, and then introduces a slip 

 of new materials. " But the most curious circum- 

 stance in the history of this little Arab, is the mode 

 by which it retains its tent ina perpendicularposture. 

 This it effects partly by attaching silken threads 

 from the protuberance at the base to the sun-ound- 

 ing surface of the leaf But, being not merely a me- 

 clianician, but a profound natural philosopher, well 

 acquainted with the properties of air, it has another 

 resource when any extraordinary violence threatens 

 to overtum its slender turret. It forms a vacuum 

 in the protuberance at the base, and this as effectually 

 fastens it to the leaf as if an air-pump had been 

 employed ! This vacuum is caused by the insect's 

 retreating, on the least alarm, up its narrow case, 

 which its body completely fills, and thus leaving the 

 space below free of air.'^ If one of these cases is 

 detached from the leaf, this fact may easily be per- 

 ceived. If the cell is suddenly seized, while the 

 insect is at the bottom, it will be found readilypulled 

 off, as the silken cords give way to a very slight 

 force ; but, if it is done more gently, the insect gets 

 time to retreat, in which event the case will become 

 so firmly fixed, that some force will be required to 

 remove it. " As if aware that, should the air get 

 admission from below, and thus render a vacuum 

 impracticable, the strongest bulwark of its fortress 

 " KiRBY and Spence's Introduction, i. 457. 



