The Characteristic of Nerve. 



207 



June 1, 1899. 



Professor T. G. BONNEY, Vice-President, in the Chair. 



A List of the Presents received was laid on the table, and thanks 

 ordered for them. 



Professor Ludwig Boltzmann, Professor Anton Dohrn, Professor 

 Emil Fischer, Dr. Georg Neumayer, and Dr. Melchior Treub, were 

 balloted for and elected Foreign Members of the Society. 



The following Papers were read : — 



I. " The Parent-rock of the Diamond in South Africa." By Professor 

 T. G. Bonney, F.E.S. 



II. " Experimental Contributions to the Theory of Heredity. A. 

 Telegony." By Professor J. C. Ewart, F.E.S. 



" The Characteristic of Nerve." By Augustus D. Waller, M.D., 

 F.RS. Eeceived February 3 — Eead February 16, 1899. 



The object of the present preliminary series of experiments was to 

 determine whether the excitability (or, as I should prefer to say in this 

 connection, the mobility) of living matter can be gauged by the rate of 

 impact of a mobilising stimulus ; in other words, whether, for various 

 kinds of more or less mobile protoplasm, an optimum stimulation- 

 gradient can be found, above and below which the curve of stimulation 

 is less perfectly adapted to the movement caused by stimulation. In, 

 e.g., the case of the rolling of a ship, there is an optimum wave-length 

 and wave-face outside the limits of which the " mobilisation " is less 

 than maximal. And just as the optimum wave-length giving greatest 

 movement by least energy harmonises with and gives therefore mea- 

 sure of the oscillation-period of a particular ship, so the optimum 

 gradient of mobilising energy producing greatest excitation by least 

 energy, might be expected to give measure of the excitation-period 

 proper to a particular tissue, and to characterise that tissue. 



The best instrument at our disposal for an examination of this point 

 is obviously a condenser, of varied capacity, charged at varied pres- 

 sure. This method of excitation has been put into effect by several 

 previous observers. Chauveau(l) first systematically studied the " law 

 of contractions," and demonstrated upon frog's nerve that the make 



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