612 BEPOET— 1889. 



Time forbids me even to attempt to explain how this theory enables us to 

 express more consistently the accepted explanations of many collateral phenomena, 

 particularly those of electrotonus. I am content to show you that it is not impos- 

 sible to regard the three phenomena, viz., chemical explosion, sudden electrical 

 change, and change of form, as all manifestations of one and the same process — as 

 products of the same mechanism. 



In plants, in certain organs or parts in which movement takes place as in 

 muscles in response to stimulation, the physiological conditions are the same or 

 similar, but the structural very diiferent ; for the effect is produced not by a change 

 of form, but by a diminution of volume of the excited part, and this consists not 

 of fibres but of cells. The way in which the diminution of volume of the whole 

 organ is brought about is by diminution of the volume of each cell, an effect which 

 can obviously be produced by flow of liquid out of the cell. At first sight there- 

 fore the difl'erences are much more striking than the resemblances. 



But it is not so in reality. For the more closely we fix our attention on the 

 elementary process rather than on the external form, the stronger appears the 

 analogy — the more complete the correspondence. The state of turgor, as it has 

 been long called by botanical physiologists, by virtue of which the framework of 

 the protoplasm of the plant retains its content with a tenacity to which I have 

 already referred, is the analogue of the state of polarisation of Bernstein. As 

 regards its state of aggregation it can scarcely be doubted that inasmuch as the 

 electrical concomitants of excitation of the plant cell so closely correspond with 

 those of muscle, here also the tagmata are cylindrical, and have their axes parallel 

 to each other. Beyond this we ought perhaps not to allow speculation to carry 

 US, but it is scarcely possible to refrain from connecting this inference with the 

 streaming UKjtion of protoplasm which in living plant cells is one of the indices of 

 vitality. If, as must I think be supposed, this movement is interstitial, i.e. due to 

 the mechanica aciion of the moving protoplasm on itself, we can most readily 

 understand its mechanism as consisting in rhythmically recurring phases of close 

 and open order in the direction of the tagmatic axes. 



In submitting this hypothesis I do not for a moment forget that the facts 

 relating to the contractility of plant cells have as yet been insufBciently investigated. 

 No one has as yet shown that when the leaf of the sensitive plant falls, or that of 

 the flytrap closes on its prey, heat is developed or oxidation takes place, but it 

 does not seem to me very rash to anticipate that if it were possible to make the 

 experiment to-morrow it would be found to be so. 



Anabolism and Cataholism. 



I have thus endeavoured, building on two principles in physiology, firstly, that 

 of the constant correlation of mechanism and action, of structure and function, 

 and secondly, the identity of plant and animal life both as regards mechanism and 

 structure — and on two experimentally ascertained elementary relations, viz. the 

 relation of living matter or protoplasm to water on the one hand and to oxygen 

 and food on the other — to present to you in part the outline or sketch of what 

 might, if I had time to complete it, be an adequate conception of the mechanism 

 and process of life as it presents itself under the simplest conditions. To complete 

 this outline, so far as I can to-day, I have but one other consideration to bring 

 before you, one which is connected with the last of my four points of departure 

 — that of the relation of oxygen to protoplasm, a relation which springs out of 

 the avidity with which, without being oxidised or even sensibly altered in chemical 

 constitution, it seizes upon oxygen and stores it for its own purposes. The con- 

 sideration which this suggests is that if the oxygen and oxidisable material are 

 constantly stored, they must either constantly or at intervals be discharged, and 

 inasmuch as we know that in every instance without exception in which heat is 

 produced or work is done, these processes have discharge of water and of carbon 

 dioxide for their concomitants, we are justified in regarding these discharges as the 

 sign of expenditure, the charging with oxygen as the sign of restitution. In other 

 words, a new characteristic of living process springs out of those we have already 



