THE CELL 55 



It; contains carbon, which we know of, under 

 one of its forms, as charcoal. It contains 

 hydrogen and oxygen, two gases which enter 

 into combination to form water, and it con- 

 tains nitrogen, another gas which with oxygen 

 makes up most of the air which we breathe. 

 These four substances are its most important 

 constituents, but in addition to this there are 

 minute quantities of other elements, notably 

 phosphorus. It is not to the number of 

 elements contained then that protoplasm owes 

 its complexity. But there can be no doubt Has prot< 



that the molecule of protoplasm, if indeed it pla f m f 



molecule 5 



is in any way correct to say that protoplasm 

 has a chemical molecule, must be" one of 

 enormous complexity. Again, however, it must 

 be insisted that we know not what may be the 

 actual state of affairs in living protoplasm, 

 indeed there is some reason to think that 

 the composition of the protoplasm in one 

 part of a cell may differ from that in another 

 part, whilst that cell is alive. " Protoplasm," 

 says Wallace,* "is so complex chemically as 

 to defy exact analysis, being an elaborate 

 structure of atoms built up into a molecule in 

 which each atom must occupy its true place, 

 like every carved stone in a Gothic Cathedral." 

 Piliiger, too, a very distinguished German 



* Man's Place in the Universe, p. 199. 



