430 l^LExMEMTAKV I'KOliLEjMS IX i'HYSlULUGY. 



equators with positive, and couseqiiently that the direction of the dis- 

 charge in the catalyte at the moment tliat the polarization disappears, 

 is from pole to equator. 



Time forbids me even to attempt to explain hov/ this theory enables 

 us to express more consistently the accepted explanations of many col- 

 lateral phenomena, particularly those of electrotonus. I am content to 

 show you that it is not impossible 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 different ; 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 fibers 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 therefore 

 the differences 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 frame-work of the protoplasm of the plant retains its con- 

 tent with a tenacity to which I have already referred, is the analogue 

 of the state of polarization of Bernstein. As regards its state of aggre- 

 gation, it can scarcely be doubted that inasmuch as the electrical con- 

 comitants of excitation of the plant cell so closely correspond with 

 those of muscle, here also the t.agmata are cylindrical, and have their 

 axes parallel to each other.- Beyond this w^e ought perhaps not to allow 

 speculation to carry us, but it is scarcely possible to refrain from con- 

 necting this inference with the streaming motion 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, /. c, due to the mechanical 

 action of the moving protoplasm on itself, we can most readily under- 

 stand its mechanism as consisting in rhythmically recurring phases 

 of close and open order in the direction of the tagmatic axes. 



I have thus endeavored — 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 experiment- 

 ally 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 in part the outline or sketch of what might (if I had 

 time to complete it) be an adequate conception of the mechanism and 

 ])rocess of life as it ])resents itself under the sim]dest conditions. 



