PLANT RESPONSE 127 



tissues of plants to those of animals ; and similarly with 

 regard to the response of digestive organs, from the 

 tentacle of the sun-dew, or the pitcher of Nepenthes, which 

 Darwin's ' Insectivorous Plants ' had brought into great 

 prominence a good few years before, to the stomachs 

 of frog, tortoise and other animals : and in all this com- 

 parative study unexpected agreements are found even of 

 detail. So from a chapter on ' the response to the stimulus 

 of light given by leaves/ our writer passes boldly to the 

 response of the retina to the same stimulus. Again, from 

 the determination of the velocity of transmission of excita- 

 tion in plant-tissues and the comparison of the conducting 

 powers of two parts of an identical nerve by the original 

 device of a ' Conductivity Balance/ we come to a new 

 method for the quantitative stimulation of nerve ; and 

 thence again to the electrical response of isolated * vegetable 

 nerve ' (isolated, that is, by the withdrawal of the fibro- 

 vascular bundle, with its conducting elements included 

 within its sheath, from the leaf-stalk of the fern), 

 in which the analogous behaviour to animal nerve is 

 demonstrated, in normal condition, under tetanisation, 

 under influence of heat and cold, and under anaesthetics, 

 like ether and chloroform. 



In such ways of investigation, at once broader in 

 scope and bolder in comparison than heretofore, while 

 more experimentally elaborated generally with improved 

 methods and newly invented and finer apparatus this 

 incursion into animal physiology proceeds, often with 

 fresh results. The further investigations into the electro- 

 physiology of nerve are too elaborate and technical for 

 outline here ; but the animal physiologist has had since 

 to reckon with them increasingly. 



It is now time to return to the earlier of these two 

 correlated volumes, the one on ' Plant Response/ and 

 to note something of its advance upon its predecessor, 

 which indeed now appears to be the introduction to 

 Bose's wide and varied inquiry in vegetable physiology 



