44 THE NATURE AND ORIGIN OF LIVING MATTER. 



Leaving: the nature of consciousness on one side, as a 

 problem altogether outside the range of science, we may, I think, 

 regard all the other properties of protoplasm as susceptible of 

 physical and chemical explanations. I do not see that this is a 

 conclusion which ought to give offence to anyone. It is the 

 natural and inevitable result of the application of scientific 

 method to the study of living matter. So long as in the non- 

 living world motion was regarded as a property of matter, which 

 needed some immaterial agent to keep it from ceasing at any 

 moment, a science of physics was not possible. In the same way 

 the continuance of the supposition of an arbitrary principle of 

 vitality which made the phenomena of protoplasm something 

 quite difierent in kind from other chemical and physical changes 

 would have deprived the science of biology of any stable founda- 

 tion. It is true that with our present knowledge we have scarcely 

 approached the ultimate problems of physiology. Yet all 

 that has been learnt, and it is no small total, has been 

 acquired on the assumption that living matter is subject to 

 ordinary physical and chemical laws. In this sense science is 

 materialistic. I use the word with some misgivings, as there is, 

 I know, a vague popular horror of a something called 

 " Materialism," which is supposed to explain away all mystery 

 from the universe. Why, the very air we breathe is full of 

 mystery ! Such fears are irrational, mere chimaeras raised by 

 ignorance and want of thought, and therefore beyond the reach 

 of argument. 



To fulfil the promise of my title I ought to add a few words 

 regarding the origin of life. This is a problem to be approached 

 with diffidence. In speaking of the nature of living matter we 

 were treating of something that we can actually see and examine, 

 but its origin is far removed. We must recognise that our 

 present state of knowledge shows a great gap between non-living 

 and living matter, and we know nothing of any development of 

 the former into the latter. We no longer believe, as some used 

 to believe, that frogs arise from a mixture of dust and rain- 

 water, that maggots are bred from decaying flesh, that bacteria 

 arise de uom in turnip infusion. At the same time we have very 

 strong reasons for thinking that at a distant epoch thi« globe 

 was in a molten condition, at a temperature which would render 

 the existence of any living beings impossible. Life must be 



