of Edinburgh, Session 1868-69. 589 
fatal action of certain doses of physostigma may be prevented by 
atropia. 
Many examples can be referred to in which several of the actions 
of various substances may be impeded, prevented, or counteracted 
by those of others. Of these we may instance the antagonism 
between the actions of physostigma and atropia and of opium and 
atropia on the iris, and also of these pairs of substances and of 
quinia and morphia on the minute blood-vessels. It is, however, 
doubtful if any absolutely demonstrated example of antagonism 
can be referred to in which the toxic action of one substance may 
be prevented by the physiological action of another. The only 
instance deserving of notice in which antagonism of the latter class 
is asserted to exist, is that between opium on the one hand, and 
belladonna, hyosciamus, and other active substances derived from 
the Solanacece on the other. The truth of this reputed antagonism 
has not, however, been established. The observations on man that 
appear to support it are found, on careful examination, to be liable 
to many objections ; while the experiments that have been made 
on the lower animals have produced evidence that is directly 
opposed to its existence. 
In bringing these experiments before the Society the author’s 
purpose has only been to show that there exists an antagonism 
between the toxic action of certain doses of physostigma and of 
belladonna or atropia. In the further investigation of this subject 
it will be necessary to determine exactly on what special actions 
this antagonism depends, and also within what limits of dosage it 
is maintained. Being concerned with two substances each of which 
possesses a number of actions, it is not unreasonable to anticipate 
that several of them are not mutually antagonistic. Above certain 
doses a region may, therefore, be entered where the non-antagonised 
actions are present in sufficient degrees to be themselves able to 
produce fatal effects. 
These, and many other important questions, remain for exam- 
ination. Their elucidation may be expected to have a direct 
bearing on the principles of therapeutics, for they require the 
demonstration of the manner in which certain accurately defined 
abnormal conditions are restored to normality by actions of an 
equally defined and accurately determined character. 
