718 The Outline of Science 



lip by 72 atoms of carbon, 112 atoms of hydrogen, 18 atoms 

 of nitrogen, all brought into association with one atom of 

 sulphur. In all protoplasm of living matter there is a mixture of 

 proteins, carbohydrates, and fats, with intricate chemical and 

 physical inter-relations. It is highly improbable that there is 

 any one substance which deserves to be called the living matter or 

 protoplasm. What we actually know is a complex and hetero- 

 geneous system in which various chemical reactions take place 

 simultaneously. There is always involved, as life goes on, a break- 

 ing down and a building up of proteins. But the riddle is still 

 unread. 



Some biologists hold the view that there is an "ultimate mole- 

 cule of life," hidden in the protoplasm, which holds the secret of 

 the endless building up and breaking down. Sir Ray Lankester 

 gives this "supreme life-stuff" the name "plastogen," and he says 

 in regard to its workings that "whilst they can be grouped with the 

 chemical and physical qualities of other bodies, they so far trans- 

 cend them in complexity and in immensity of result the whole 

 creation of plant and animal life that their appearance con- 

 stitutes, in effect, a new departure, a sudden, and to us, unac- 

 countable acquirement. But then we must remember that it is 

 also an unaccountable thing to us that water suddenly becomes ice 

 at a low temperature and suddenly becomes vapour at a high 

 temperature, even if we are able to imagine the mechanism which 

 necessitates these changes. We cannot 'explain' the nature of 

 things. Even though we can classify them and arrange them in 

 order, and more or less satisfactorily guess what their inner 

 mechanism is, we cannot, in our present state of knowledge, trace 

 them in detail to a first beginning." 



Some of the elements in their natural conditions are gaseous, 

 like oxygen, hydrogen, nitrogen, chlorine, etc.; mercury and 



