SECTION D—ZOOLOGY. 
THE MECHANICAL VIEW OF LIFE 
ADDRESS BY 
DR: J."GRAY)’F.RIS:, 
PRESIDENT OF THE SECTION. 
EAcu year it becomes more difficult to review the progress which is being 
made in the diverse fields of modern zoology, for as individuals we are 
necessarily specialists, and we tend to forget that the greatest contribu- 
tion which zoology has ever made to human thought was not the result 
of a specialised inquiry. The concept of organic evolution was, on the 
contrary, a brilliant process of integration from every branch of the 
subject, which spread its effect far beyond the confines of zoology itself. 
Although it is impracticable to review, even in the most general terms, 
the progress of the science as a whole, it is perhaps possible to take stock 
of one particular branch of the subject and to discuss its contributions 
towards problems which are of some general scientific and human interest. 
To an increasing extent, experimental zoologists are borrowing the 
weapons of physical chemistry, and possibly the time has come to consider 
the general point of view which underlies this type of attack on zoological 
problems. What is our conception of the essential nature of the living 
organism? Do we believe that the activity of living matter and its 
potentiality for change can be expressed adequately in terms of physical 
units? Do we incline to the belief that living animals have been evolved 
from inanimate matter ? 
The aim of experimental biologists is to express the living organism in 
terms of its dynamic activities and to consider its structure as an active 
and functional machine. It is not infrequently suggested that this is the 
province of the physiologist and the biochemist. I venture to think that 
this is not the case. Let us consider one of the fundamental tissues of 
an animal’s body from the point of view of the physiologist and from that 
of the zoologist. ‘To the physiologist, a muscle is all but invariably an 
isolated preparation functioning under conditions which are often remote 
from those which exist in the body of the organism. Such preparations 
have thrown light on the phenomena of muscular contraction, and on the 
process whereby the muscle is induced to contract when it receives a 
nervous impulse. On the other hand, how many physiologists know, or 
are even interested to know, how a frog jumps? ‘To the zoologist a 
frog’s sartorius should represent an essential part of the locomotory 
machine ; it must be studied im situ and in a way which will illuminate, 
not the nature of a muscular twitch, but the behaviour of the animal in 
its own natural habitat. It is idle to suggest that there is not much 
common ground between physiology and experimental zoology, but, 
from a broad standpoint, the conception of the organism as a single living 
