so 6 Mr. Brodie's Experiments and Observations 
in the healing art. This consideration, I should hope, will be 
regarded as a sufficient apology for my pursuing a mode of 
inquiry by means of experiments on brute animals, of w hich 
we might well question the propriety, if no other purpose 
were to be answered by it than the gratification of curiosity. 
In my former communication on this subject, I entered into a 
detailed account of the majority of my experiments. This I 
conceived necessary, because in the outset of the inquiry I had 
been led to expect that even the same poison might not always 
operate precisely in the same manner; but I have since had abun- 
dant proof, that in essential circumstances there is but little 
variety in the effects produced by poisons of any description, 
when employed on animals of the same, or even of different 
species, beyond what may be referred to the difference in the 
quantity, or mode of application of the poison, or of the age 
and power of the animal. This will explain the reason of my 
not detailing, in the present communication, so many of the 
individual experiments from which my conclusions are drawn, 
as in the former; at the same time I have not been less care- 
ful to avoid drawing general conclusions from only a limited 
number of facts. Should these conclusions prove fewer, and 
of less importance than might be expected, such defects will, 
I trust, be regarded with indulgence; at least by those, who are 
aware of the difficulty of conducting a series of physiological 
experiments ; of the time, which they necessarily occupy ; of 
the numerous sources of fallacy and failure which exist ; and 
of the laborious attention to the minutest circumstances, which 
is in consequence necessary in order to avoid being led into 
error. 
