509 
of Edinburgh, Session 1870-71. 
to 12 grain; and with three and a-half times the minimum fatal 
dose of physostigma, with doses of atropia ranging from *1 grain to 
'2 grain. Successful antagonism could not be obtained above this 
dose, and, accordingly, three and a-half times the minimum fatal 
dose of physostigma would appear to be about the largest quantity 
whose lethal action may he prevented by administering atropia 
five minutes previously. 
A similar series of experiments has been made, in which phy- 
sostigma was administered five minutes before atropia, and the 
results were essentially the same, excepting that the region of suc- 
cessful antagonism was found to be more limited. 
These results may be graphically represented by means of 
diagrams. The diagram accompanying this abstract is a reduced 
copy of one exhibited by the author to illustrate the series of ex- 
periments above described, in which atropia was administered five 
minutes before physostigma. The experiments that terminated in 
death are marked by crosses, and those that terminated in recovery 
by dots, while the position assigned to each experiment is deter- 
mined by the doses of physostigma and atropia, calculated, when 
necessary, for three pounds weight of rabbit. The doses of atropia 
increase according to the distance, in a horizontal direction, from 
the perpendicular line forming the left margin of the diagram, and 
the increase proceeds at the rate of one-tenth of a grain for each 
subdivision of the horizontal lines. The doses of physostigma 
increase from below upwards, the same horizontal line always 
representing the same dose of physostigma. The curved line, 
a b c, separates the fatal experiments (crosses) from those which 
terminated in recovery (dots), and, accordingly, it defines the region 
of successful antagonism — a region further distinguished in the 
diagram by the absence of shading. The darkly shaded region is 
that in which antagonism is not successful, death being produced 
because the doses of atropia given in combination with one or 
other of the doses of physostigma employed are either too small or 
too large. In the lightly shaded region, below the horizontal line 
representing the minimum fatal dose of physostigma, the doses of 
physostigma are too small of themselves to cause death. The 
lateral extension of the diagram is, however, insufficient to exhibit 
the chief interest of this region. Were the diagram extended, it 
VOL. vii. 3 y 
