36 THE BIOLOGICAL PROBLEM 



wall falls to one-tenth of its value when the cell dies. 

 (Osterhout). 



In brief, the vital equilibria which bring infinitely complex 

 structures into play are never absolutely comparable to the 

 physical and chemical equilibria. 'True equilibrium is death,' 

 said Bayhss. 



Now that we have shown some of the pitfalls which the 

 chemist and physico-chemist encounters in his study of living 

 matter, it is only fair to add that a great number of biological 

 problems can be solved by means of chemical and physical 

 methods, and even can only be solved that way. Amongst 

 these, luckily, are those which are of the greatest interest to 

 humanity, namely the problems of immunity in general, pro- 

 tection against infectious disease, as well as a great number of 

 pathological and therapeutical problems. After the preceding 

 rather discouraging pages we will try to give a slightly ipore 

 optimistic note. 



