THE ACTIONS OF PHYSOSTIGMA AND ATROPIA. 609 



absorbed. The decrease may be referred to various causes, such as the elimi- 

 nation of the atropia, or its destruction in the tissues, or it may be due merely 

 to a diminution in the degree of the actions produced by this substance, 

 altogether independent of either elimination or destruction. 



To whatever cause we refer the decrease in intensity of the actions of atropia, 

 in some exceptional circumstances, connected in all probability with the condition 

 of the animal employed in the experiment, a delay seems to occur in the rapidity 

 with which those actions are decreased, that are accountable for the production 

 of death when the interval by which the administration of the atropia precedes 

 that of the physostigma is one of twenty minutes, or one of shorter duration. 

 The occurrence of this delay is well illustrated by the fatal termination of 

 Experiments 323 and 324 ; in the first of which the atropia was administered 

 sixty-five minutes, and in the other one hundred and five minutes before the 

 physostigma. In both experiments, the symptoms that were observed closely 

 resemble those of the experiments in which an interval too brief for the pro- 

 duction of successful antagonism had separated the administration of the two 

 substances. A reference to the description of these experiments in the Tabular 

 Summary will confirm this statement. 



The various results of this, the third series of experiments, have been 

 graphically represented in Diagram 6 (Plate XXV.). This diagram agrees 

 with the diagrams already described in showing by distance from one and the 

 other of two straight lines placed at right angles to one another, what amount 

 of one and the other respectively of two variables is present in each of certain 

 combinations of them further diagrammatically distinguished by the character 

 of the mark indicating their diagrammatic position into fatal and non-fatal : 

 and differs from them in substituting for one of their variables, namely, the 

 dose of physostigma, a new variable, namely, a varying interval of time separat- 

 ing the administration of the one substance from that of the other ; the differ- 

 ence depending on the fact, that while in the two previous series of experiments 

 the dose of atropia and the dose of physostigma varied, and the interval of time 

 separating the administration of the one substance from that of the other was 

 constant, in the present series the dose of atropia and the interval of time 

 separating the administration of the one substance from that of the other varied, 

 and the dose of physostigma was constant. 



The representation of the order in which the administration of the one sub- 

 stance stands to that of the other, is provided for by the arrangement that in 

 the representation of length of interval of time by distance from the line of zero 

 interval, that distance is taken on the upper or on the under side respectively 

 of that horizontal line, according as the administration of the atropia precedes 

 or follows that of the physostigma. Each of the equal subdivisions of distance 

 from the line of zero interval, which aremarked out by the lines drawn parallel 



VOL. XXVI. PART III. 7 T 



