THE PROBLEM OF THE LIVING WORLD 



long road to travel, that unexplored fields are yet 

 innumerable, and that no problem can be considered 

 insoluble so long as it has not been subjected to a 

 thorough investigation by means of all available 

 methods. If we consider that the number of these 

 methods increases each day, if we remember that 

 discoveries which seem quite insignificant are often 

 pregnant with the most important deductions from 

 Galvani to the telegraph and the telephone one 

 small century only has elapsed we may fairly con- 

 clude that a problem which hardly admits to-day of 

 any investigation may suddenly be solved to-morrow. 

 I may be allowed to quote an instance among many. 

 Some forty years ago a young man spent a long time 

 in the seemingly very speculative and idle study of 

 dissymmetry and symmetry in various crystals. The 

 practical value of such investigation seemed to be 

 nought, and at all events it had no interest save for 

 the elucidation of some points in crystallography. 

 But this investigation led logically to a study of 

 fermentation, and the final outcome of Pasteur's 

 earliest work has been leaving out the step- 

 ping stones the discovery of the real cause of 

 a large number of diseases, the cure of one of 

 them, and the expectation, based on facts, that 

 all of these diseases can be defeated by appropriate 

 methods. Little causes have great effects, and no 



