CHANGES IN SCIENTIFIC OPINION 9 



But there are others who refuse to accept this Neo- 

 explanation of life and to set forward the arguments 

 in favour of their point of view is the object of this 

 little book. And first it may be pointed out that 

 some of those processes in the human body which 

 forty or fifty years ago seemed most clearly to be 

 mechanical in their nature, some of those processes 

 to which Burdon Sanderson alluded in the quota- 

 tion above, some of these processes have, in later 

 years, been shown to be wholly inexplicable in 

 terms of a mechanical explanation. One or two 

 examples of what is meant will make matters clear 

 to the unscientific reader. 



The food which we take into our stomachs is 

 there and elsewhere in the alimentary canal acted 

 upon by various juices and converted into a 

 digested semi-fluid substance capable of absorption 

 and utilisation by the body. This substance passes 

 through the cells which line a portion of the 

 alimentary tract, and it was formerly supposed that 

 this passage through the cells was of the nature of 

 a filtration, or at least of an osmotic process such 

 as may take place through a dead animal mem- 

 brane. 



But more recent experiments have shown that 

 the occurrences which take place cannot be ex- 

 plained in any such mechanical way, but that there 

 is another factor or there are other factors at work 



