THE PLACE OF BIOLOGY. 45 



probably lead nowhere, because essential points are 

 likely to be neglected at the expense of trivial details. 

 Respiration is only one aspect of a group of phenomena, 

 which can only be grasped as a connected whole if they 

 are not wrongly or superficially grasped. If we could 

 examine a large living animal piece by piece with a high- 

 power microscope, we should see a vast number of cells, 

 but we could probably form no idea of the animal as a 

 whole, and very little idea of the activities of the cells ; 

 and if the magnification were increased a thousand- 

 fold more, we should see nothing of the cells, and should 

 only be lost in a bewildering whirl. It is doubtless true 

 in a certain sense that the life of an organism is the 

 " sum " of its activities ; but it is equally true that these 

 activities can only be grasped individually as activities 

 of a whole. The true aim of physiology is to grasp them 

 in this sense ; and if we accept this, we can see that 

 physiology is making steady and rapid progress. If, 

 on the other hand, we assume the mechanistic or the 

 vitalistic theory of life, we can see no progress whatever 

 towards a successful application of either hypothesis. 



This may perhaps seem a strong statement, for have 

 we not acquired a great deal of knowledge which can 

 only be stated in terms of the physics and chemistry of 

 the body ? Surely all this is physiological progress. 

 It is physiological progress just in so far as the physical 

 and chemical data can be interpreted in terms of organic 

 activity. As instances of what I mean, I need only refer 

 to such cases as the function of the respiratory move- 

 ments, or of the digestive ferments, or of those recently 

 discovered and singularly beautiful adjustments by 

 which the partial pressures of both oxygen and carbon 



