178 [Proc. B. N. F. C, 



the distinctions which were held to separate plants from animals 

 are non-existent, and that life, as manifested by protoplasm, 

 whether animal or vegetable, is always the same. Taking the 

 common " sensitive plant" {Mimosa pudica) as the most striking 

 example of a plant possessing moveable leaves, three distinct 

 though closely connected sets of moveable phenomena are 

 shown. First, those due to external stimulation of touch, or 

 mechanical, chemical, or electric forces ; second, those due to 

 the paratonic influence of light, forming the class of nyctitropic 

 movements or night-turning ; third, those that form the class 

 of automatic or spontaneous movements, often affected by 

 external stimuli, such as light, but not caused by them. The 

 various mechanism by which all these are effected was described 

 in detail, and the difference between the position assumed by 

 the leaves under stimulation and during sleep was pointed out. 

 The beneficial effect of sleep movements, whereby, as Darwin 

 has shown, only one-fourth of the daylight surface of the plant 

 is exposed to the loss of temperature by radiation at night, was 

 discussed in detail. Some account was also given of the spon- 

 taneous movements of the telegraph plant of India, as well as 

 of the Mimosa. This class of movements is in reality the most 

 important, though not the most conspicuous in plant life. The 

 action of external influences on the movements and conditions 

 on which irritability depends were then discussed, and the rigid 

 position and loss of movement caused by prolonged exposure to 

 darkness, or too low or too high a temperature, or to drought, 

 were described. The asphyxia caused by loss of oxygen, and 

 the effects of chloroform, ether, and other anasthetics were 

 mentioned. Turning to the morphological side, the minute 

 anatomical structure of the pulvinus at the base of the leafstalk 

 was shown to be the same in all cases which had been investi- 

 gated, and the possession by it of the structural peculiarities best 

 fitted for its purposes demonstrated. A consideration of the 

 exact changes which go on in the mechanism in the diflferent 

 cases, and the causes of the movements, then followed. The 

 effects of over-stimulation of vigorous shaking (as when taken 



