596 DR THOMAS R. FRASER ON THE ANTAGONISM BETWEEN 



acting power of atropia when it is administered five minutes before, than when 

 it is administered five minutes after physostigma. It has been shown that in 

 the one case, three and a half times the minimum-lethal dose can be rendered 

 non-fatal, whereas in the other, only three times the minimum-lethal dose can 

 be successfully counteracted; and not only does this difference exist, but the 

 range of the doses of atropia that can prevent the lethal action of any given 

 dose of physostigma is also greater in the former case than in the latter. 



The greater irregularity of the curved line a b c in Diagram 3 than in 

 Diagram 1 renders very manifest certain other of the results, which also, it is 

 true, have already been mentioned in the description of the experiments, but 

 which cannot be so well appreciated from a mere verbal description as from 

 such a graphic representation as is afforded by the diagrams. It will be re- 

 membered that this line separates the experiments that terminated in death 

 from those that terminated in recovery. For convenience of description, it may 

 be regarded as consisting of two portions, a b and b c, — the former separating 

 the experiments that terminated in recovery after the smallest successfully 

 counteracting doses of atropia from those that terminated in death after still 

 smaller doses of atropia, and the latter separating the experiments that ter- 

 minated in recovery after the largest successfully counteracting doses of atropia 

 from those that terminated in death after still larger doses of atropia. In con- 

 nection with each of these portions of the line a b c, there are several points 

 to which attention may be directed. 



In Diagram 1, the portion b c is a straight line, because, when physostigma 

 is administered five minutes after atropia, the largest doses of atropia that 

 can produce successful counteraction differ from each other by one grain for 

 each difference by half the minimum-lethal dose in the quantity of physostigma. 

 In Diagram 3, however, b c is a curved line, because when physostigma is 

 administered five minutes before atropia, the largest successfully counteracting 

 doses of atropia do not diminish regularly as the doses of physostigma are re- 

 gularly increased. 



The greater irregularity of the curved line a b c in. Diagram 3 than in 

 Diagram 1 is apparent also in the portion a b; and it will be seen that this 

 portion has a less perpendicular direction, as well as a less straight course, in 

 the former than in the latter diagram. 



In both diagrams, the steep rise of a b contrasts in a marked manner 

 with the gradual descent of b c. This contrast brings into prominent relief 

 those already mentioned results that show the smallest of the various 

 doses of atropia capable of successfully counteracting different doses of 

 physostigma to differ from each other much less than the largest. It has been 

 ascertained by the first series of experiments, that when atropia is adminis- 

 tered five minutes before physostigma, the difference between the smallest 



