936 



SCIENCE. 



[N. S. Vol. XVI. No. 415. 



sented by the plant at rest and diiring ac- 

 tivity. Very little work lias so far been 

 done in this direction, and our knowledge 

 of the subject is materially less than that 

 concerning similar phenomena in muscle 

 and nerve. Still a beginning has been 

 made, and we have observations on record 

 due to Waller and to Bose which are of the 

 greatest interest, not only because they 

 show a great correspondence in behavior 

 between animal and vegetable structures, 

 but on account of their possible importance 

 in determining the character of many of 

 the metabolic processes and the forces at 

 work in the tissues. 



Some very striking results were only a 

 few months ago published by Bose on the 

 electric response in ordinary plants to me- 

 chanical stimulation. He arranged a piece 

 of vegetable substance, such as the petiole 

 of the horse-chestnut, or the root of a cai-- 

 rot or a radish, so that it was connected 

 with a galvanometer by two non-polarizable 

 electrodes. The uninjured tissue gave little 

 or no evidence of the existence of electrical 

 currents ; but if a small area of its surface 

 was killed by a burn or the application of 

 a few drops of strong potash, a current 

 was observed to flow in the stalk from 

 the injured to the uninjured area, just 

 as is the case in animal tissue. The 

 potential difference in a typical experi- 

 ment amounted to .12 volt. The tissue 

 was then stimulated, either by tapping or 

 by a torsion through a certain angle, 

 and at once a negative variation or cur- 

 rent of action was indicated, the potential 

 difference being decreased by .026 volt. 

 Very soon after the cessation of the stim- 

 ulus the tissue recovered and the current 

 of rest flowed as before. Bose 's investiga- 

 tions extended considerably beyond this 

 point, and established a very close sim- 

 ilarity in behavior between the vegetable 

 substance and the nerves of animals. 

 Summation effects were observed, and 



fatigue effects demonstrated, while it was 

 definitely shown that the responses were 

 physiological. They ceased entirely as soon 

 as the piece of tissue was killed by heating. 

 This remarkable demonstration of simi- 

 lar electrical properties to those possessed 

 by nerve strengthens very greatly the view 

 of the conduction of stimuli in the plant 

 by means of the protoplasmic threads which 

 have been demonstrated by Gardiner and 

 others to exist throughout the plant, uni- 

 ting cell to cell into one coherent whole. 



Much remains to be done in this field; 

 indeed, not more than a beginning has been 

 made. The electrical accompaniments to 

 response to stimuli have been investigated 

 by Burden Sanderson in the case otDioncm, 

 but many other instances are still awaiting 

 examination. The peculiar phenomena of 

 electrotonus and their relation to stimulus 

 have so far only been observed in animals. 

 These observations strengthen consider- 

 ably the view of the identical nature of 

 animal and vegetable protoplasm which 

 has in recent years come into prominence, 

 and which is receiving more and more sup- 

 port in all directions. 



These electrical currents, following me- 

 chanical action, which no doubt is accom- 

 panied by chemical change, make us ask 

 whether electrical phenomena do not in all 

 probability accompany the slow chemical 

 actions which we call metabolism. The 

 view that electrical energy is concerned in 

 the processes of photosynthesis, suggested 

 in an earlier part of this address, is cer- 

 tainly not weakened by a consideration of 

 these phenomena. 



The probability of the transmission of 

 stimuli through vegetable tissue along the 

 protoplasmic threads, extending from cell 

 to cell, has been supported during the last 

 year or two by some remarkable observa- 

 tions claimed to have been made by Nemee 

 on cei'tain roots and other organs. He 

 says he has succeeded in demonstrating a 



