372 Report of the Committee for conducting Inquiries [Feb. 28, 



organs in men, moths, sweet peas, and other things at various periods 

 of life, made it seem probable that if selective destruction could 

 be shown to occur in these cases, the expression for intensity of 

 destruction, in terms of the deviation, would in all these cases be of 

 the same form as that already arrived at. That is to say, the 

 expression for the effect of physiological accidents of a number of 

 different kinds, affecting a number of organisms in no way specially 

 alike, is probably always of the same form. The question at once 

 occurred, whether this expression might not be of general applica- 

 tion, as a measure of the effect of physiological accidents upon the 

 animal body. 



The most convenient case in which to look for an answer to this 

 question is the case of muscular tissue, in which the effect of acci- 

 dents of stimulus can be readily measured. The recent paper of 

 Cyboulski and Zanietowski (Pniiger's ' Archiv f. Physiologic,' 

 Bd. 56, p. 45) gives an excellent series of data for determining the 

 relation between energy of stimulus applied to a nerve, and effect 

 upon the muscle, as measured by energy of external work performed 

 in contraction. These observers give a large series of tables, in 

 which the energy of stimulus, applied by discharging a condenser 

 of known electrical capacity through a nerve, is given in one 

 column, and in another is the work done by the muscle stimulated,, 

 measured by the height through which a known mass is lifted. 



As is well known, the application of stimuli of less than a certain 

 magnitude produces no muscular contraction ; but if the maximum 

 stimulus which can be applied without causing a contraction be 

 reckoned as zero, the subsequent relation between stimulus and con- 

 traction does, in fact, agree very closely with that indicated by suc- 

 cessive values of the quantity 1 e~ hx *. 



In spite of the evident care and skill with which Cyboulski and 

 Zanietowski have performed their experiments, their curves are 

 slightly irregular. In order to minimise the effect of these slight 

 irregularities, three of their results were treated in the following 

 way : In each system of observations the maximum subliminal 

 stimulus was subtracted from the magnitude of the applied stimulus. 

 in each case; the three numbers representing the height of the 

 muscle contraction for unit stimulus beyond this point in the three 

 cases were added together; and so on throughout. The result is 

 plotted in fig. 5, the height of the sum of three contractions being 

 indicated by the ordinates of the points O ; the intensity of the cor- 

 responding stimulus, minus the subliminal stimulus, being measured 

 along the abscissa. 



The dotted curve is given by 



g = l- e -* 2 /( 8 'i 5 ) 2 , 



