TRANSACTIONS OF SECTION K. 797 



of the aleurone gi'ain, a double phosphate of calcium and magnesium. The occur- 

 rence of this body points to a considerable interaction of various substances existinp;- 

 in the seeds, the phosphorus apparently coming from the globoids and the nitrogen 

 from the proteids. Instead therefore of the fat being transformed into sugar it 

 seems certain that a very considerable metabolism is set up, in which the various 

 constituents of the endosperm interact very freely together. I am informed by 

 Mr. Biffin, who has investigated the histological changes accompanying the 

 germination, that the protoplasm of the endosperm cells appears to increase in 

 amount very greatly during the early stages. The observations suggest a very 

 vigorous resumption of metabolic activity by the cells of the endosperm, in the 

 course of which the various reserves are brought into relation with the living 

 substance of the cells and a number of new products are formed to minister to the 

 nutrition of the growing embryo. The formation of the sugars may more probably 

 be referred to the renewed activity of the protoplasm of the parent gametophyte 

 than to a direct transformation of the fat imder the influence of the embryo. 

 Further researches upon a large variety of seeds appear necessary to give us a true 

 idea of the chemical processes of germination. What now appears probable in the 

 case of fatty seeds may prove to be true also in the case of those which have other 

 varieties of reserve material. 



I have already alluded to the problems concerning the electrical phenomena 

 presented by the plant at rest and during activity. Very little work has 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 corre- 

 spondence in behaviour 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 mechanical stimulation. He arranged 

 a piece of vegetable substance, such as the petiole of the horse-chestnut, or the root 

 of a carrot or a radish, so that it was connected with a galvanometer by two non- 

 polarisable 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 experiment amounted to 

 0"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 current of action was 

 indicated, the potential difference being decreased by •026 volt. Very soon after 

 the cessation of the stimulus the tissue recovered and the current of rest flowed 

 as before. Bose's investigations extended considerably beyond this point, and 

 established a very close similarity in behaviour 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 similar 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, uniting cell to cell into one 

 coherent whole. 



Much remains to be done in this field ; indeed, not more than a beginning iias 

 been made. The electrical accompaniments to response to stimuli have been 

 investigated by Burdon Sanderson in the case of Dioncea, 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 considerably 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 support in all directions. 



