18 WHAT IS LIFE 



The tiny mass of protoplasm, though we now know 

 that it is by no means structureless, would seem to 

 the casual observer to be an object whose possi- 

 bilities must soon be exhausted. Yet the more 

 microscopes are improved, the more methods of 

 staining and of observation are perfected, the more 

 the cell is studied, the greater are the mysteries 

 which it is found to contain. Again we may quote 

 from Wilson, the highest authority on this subject, 

 who expresses the opinion that " the recent advance 

 of discovery has not tended to simplify our con- 

 ceptions of cell-life, but has rather led to an 

 emphasised sense of the diversity and complexity 

 of its problems ". 



Schwann, when he first enunciated the cell- 

 theory, thought that he had disposed of the question 

 of vitalism once for all and in a sense contrary to 

 that theory of life. But Schwann was mistaken 

 and the theory on which he based his conclusion 

 has since been shown to be incorrect. What 

 Schwann did was to shift the question to a smaller 

 region, but in doing so he by no means made it an 

 easier question to be solved. 



Since then the cell is the basis of all biological 

 inquiries it will be well for us to commence our 

 quest by briefly considering its characters and 

 structure. 



The cell (see fig. i), speaking in the most general 



