Philosophical Conceptions of Life. 263 
tions are not sufficiently numerous, or free from objections, 
to be accepted without question as proof that an increased 
supply of blood to the brain invariably accompanies mental 
effort, they are certainly sufficient to encourage further labour 
in this interesting field. 
But if the arguments in favour of the purely material nature 
of our mental operations that have been based upon the im- 
perfect results of the three lines of investigation I have just 
referred to must be rejected as utterly fallacious, what shall 
we say of the logic that attempts to draw a similar conclusion 
from the results of those inquiries into the phenomena of 
personal equation which aim at determining the time that 
must be allowed for the mental operation involved? * Do we, 
then, indeed need the beautiful experiments of Hirsch and 
Donderst to prove that thought occupies time? Whence, 
indeed, do we derive our primitive conceptions of time save 
from our consciousness of the succession of thought? And 
how could even the shortest time be occupied by even an 
infinite number of thoughts if each thought did not occupy at 
least some time, however brief ? 
I have thus, gentlemen, attempted to show that we are 
logically compelled to invoke the existence of a vital principle 
in order to account for certain important groups of phenomena 
occurring in living beings which cannot possibly be explained 
by the chemical and physical forces of the universe. ‘These 
phenomena form a series, at one end of which we find the mere 
irritability or sensibility of the humblest mass of living pro- 
toplasm ; at the other the reasoning faculty of the human 
mind. From the one extreme of this series to the other I 
recognize the manifestations of the vital principle. I wil- 
lingly confess that I know nothing of the ultimate nature of 
this principle, except that it must be very different from the 
chemical and physical forces whose operations I have learned 
to recognize in the organic as well as in the inorganic world ; 
nevertheless I am compelled by my study of the phenomena 
to conclude that it exists. I know that Mr, Huxley, only 
last summer, declared in the International Medical Congress 
at London, that the doctrine of a vital principle is the ‘‘ asylum 
ignorantie of physiologists ”’{; but this ancient sarcasm has 
now been applied to so many things that it has long since lost 
whatever sting it may once have possessed, when it was fresh 
* Barker, p. 11, op. cit. supra. 
+ Hirsch, “ Détermination télégraphique de la différence de longitude 
entre les observatoires de Genéve et de Neuchatel,” Genéve et Bale, 1864. 
Donders, in Reichert and Du Bois-Reymond’s Archiv, 1868, p. 657. 
} T. H. Huxley, “The Connexion of the Biological Sciences with Medi- 
cine,” ‘ The Popular Science Monthly,’ October 1881, p. 800, 
