( 61 ) 
Similar experiments as described by me, were performed by 
Winker and VAN WayEnsurG some years before. The method followed 
by them, which slightly deviated from mine, enabled them to extend 
the experiment only over a small interval of variation of concentration. 
They concluded for this small interval, that the reflex-apparatus of 
the frog follows the law of Frenxer *). In the experiments communi- 
cated by them slight deviations from this law proved to occur and 
it was with the purpose of learning something about these deviations. 
that I repeated these experiments extended over a greater interval. 
Table I, H, Ill and IV represent four of these experiments. If we 
take A as the value of the stimulus in physical measure (i.e. the 
concentration of the solution of the acid in which the leg is immerged) 
and if we take A R as the value of the increment of this stimulus 
which is required to call forth a change in the system, the quotient 
ES Bve, ; ee 
a is not constant, but in general a function of R. 
L 
OUDE PLO 90 | Gr MO tO? aD 
Fig. V (table I, exper. 4). 
Gh 70 80: TA ZE CAD OVS OCS 70 
Fig. VI (table II, exper. 35). 
OP Oa tn See en ed go Wo wo Zo Jo 
Fig. VII (table IV, exper. 14). 
1) Van Wayensere, Dissertation 1897. pag. 117, 
