294 DIONiEA MUSCIPULA. Chap. XIII. 



between the lobes, one re-expanded after two days ; 

 a second after seven days ; and the third after nine 

 days. The leaf which closed, owing to a drop of the 

 solution having adhered to one of the filaments, 

 opened after two days. 



I was surprised to find on two occasions that the 

 heat from the rays of the sun, concentrated by a lens 

 on the bases of several filaments, so that they were 

 scorched and discoloured, did not cause any move- 

 ment ; though the leaves were active, as they closed, 

 though rather slowly, when a filament on the opposite 

 side was touched. On a third trial, a fresh leaf closed 

 after a time, though very slowly ; the rate not being 

 increased by one of the filaments, which had not been 

 injured, being touched. After a day these three leaves 

 opened, and were fairly sensitive when the uninjured 

 filaments were touched. The sudden immersion of a 

 leaf into boiling water does not cause it to close. 

 Judging from the analogy of Drosera, the heat in 

 these several cases was too great and too suddenly 

 applied. The surface of the blade is very slightly 

 sensitive ; it may be freely and roughly handled, with- 

 out any movement being caused. A leaf was scratched 

 rather hard with a needle, but did not close ; but when 

 the triangular space between the three filaments on 

 another leaf was similarly scratched, the lobes closed. 

 They always closed when the blade or midrib was 

 deeply pricked or cut. Inorganic bodies, even of large 

 size, such as bits of stone, glass, &c. — or organic bodies 

 not containing soluble nitrogenous matter, such as bits 

 of wood, cork, moss, — or bodies containing soluble 

 nitrogenous matter, if perfectly dry, such as bits of 

 meat, albumen, gelatine, &c., may be long left (and 

 many were tried) on the lobes, and no movement is 

 excited. The result, however, is widely different, as we 



