VI PREFACE 



which causes infectious diseases, and hence constitutes a 

 living entity, is at the same time a substance which can be 

 obtained in pure form as crystals. Here is indeed a sub- 

 stance which is an enzyme capable of regenerating itself in 

 a natural environment. 



Through Stanley's epoch-making discovery, more definite 

 assumptions on the origin of life can now be made than ever 

 before. A plain presentation of all pertaining facts has here 

 been attempted. I would welcome suggestions and con- 

 structive criticism from those who think that some of the 

 ideas in this book deserve discussion. 



R. Beutner. 



Philadelphia, October 1938. 



