154 THE JOURNAL OF BOTANY 



The author states it to have been his aim to make the plant 

 accurately self-recording and subject to automatic stimulus, so as 

 to eliminate as far as possible the personal factor from the experi- 

 ments. 



Only those with like aims can appreciate to the full the 

 success that Prof. Chunder Bose has attained in this direction, 

 but the veriest tyro must be struck with the beauty and pre- 

 cision of his automatic inventions — the oscillating recorder and 

 the resonant recorder. In both, friction between the writing 

 point and the writing surface is overcome by intermittent contact ; 

 in the former by vibration of the writing surface, in the latter by 

 vibration of the writing point, The resonant recorder was invented 

 to provide a means of recording minute time- measurements of 

 hundredths of seconds. This can be done very accurately by 

 means of the intermittent recorder, providing that the oscillation 

 period remain constant. The author has very ingeniously made 

 use of tlie principle of resonance and ensured regularity of contact 

 by timing electro-magnetic impulses to synchronize with the 

 natural frequency of the recording index. 



Prof. Chunder Bose has also used greatly improved methods 

 of stimulation, capable of quantitative variation, and including 

 various electric and electro-thermal methods of excitation. 



With these improved methods he has been able to analyze 

 experimentally the phenomena of stimulus and response, as seen 

 in the sensitive plants Mimosa, Biopliytum, &c. One of the most 

 successful results thus obtained is the demonstration of a latent 

 period strictly comparable to that shown by animal muscle under 

 stimulation. 



The ordinary fall of Mimosa leaf under stimulation is accom- 

 panied by development of a galvanometric negativity, but it is 

 found that, when the stimulus is applied at some distance from 

 the responding organ, a slight positive response appears before 

 the much more marked negative one. The author claims that his 

 experiments show that all stimulations are dual, but that unless 

 separated by time of travel, the stronger masks the weaker 

 effect. 



Prof. Chunder Bose's main thesis is that the plant exhibits 

 true physiological phenomena of excitation, conduction and con- 

 traction, and that there is the most striking parallelism between 

 muscle action and plant movement. Thus the plant shows the 

 additive effect of repetition of minute stimuli ; increase of response 

 with increase of stimulus, and, most striking of all, a complete 

 reversal of direction of movement after over-stimulation. The 

 latter fatigue phenomenon strictly parallel with relaxation of 

 muscle on over-stimulation. 



Our author, believing Pfeffer's results to have been incon- 

 clusive, has paid particular attention to the question of the trans- 

 mission of stimulus, and claims, and we think rightly, that the 

 present more extensive experiments prove the co-operation of the 

 living protoplasm in the process ; in short, that it is a physio- 

 logical and not merely a physical conduction. 



