i8o SCIENCE AND IMMORTALITY 



We have looked for a moment at the atoms 

 which compose protoplasm. Let us look now for a 

 moment at the molecules they make. A molecule 

 of water contains two atoms of hydrogen and one 

 of oxygen ; a molecule of sulphuric acid contains 

 two atoms of hydrogen, one of sulphur, and four 

 of oxygen ; but a molecule of protoplasm is much 

 larger than these, and contains no less than eight 

 or nine hundred atoms, each of these, again, accord- 

 ing to modern physics, being a veritable miniature 

 solar system. The individual atoms, as we have 

 seen, have no very remarkable properties, and in 

 certain conjunctions and combinations they seem 

 as stagnant as a stone ; yet conjoined and inter- 

 woven in the massive molecule of the protoplasm, 

 and grouped together into the structures known 

 as cells, they have the wonderful properties known 

 as vital functions. 



An individual molecule of protoplasm has 

 probably as little vital function as the individual 

 atoms of which it is composed : the physical basis 

 of life is a contexture of molecules — a tissue of 

 molecules, not massed together anyhow, but 

 arranged in a complicated manner so as to show 

 special structural features — a nucleus, etc. — when 

 viewed through the microscope. The size of these 

 molecular units of life varies ; but it has been 

 calculated that the smallest cell known must con- 



