PREFACE 



Occasionally one hears today the statement 

 that we haye come to realize that we know noth- 

 ing about evolution. This point of yiew is a 

 healthy reaction to the oyer-confident belief 

 that we knew everything about evolution. 

 But there are those rash enougli to think that 

 in the last few years we have learned more 

 about evolution than we might have hoped to 

 know a few years ago. A critique therefore 

 not only becomes a criticism of the older evi- 

 dence but an appreciation of the new evidence. 



In the first lecture an attempt is made to put 

 a new valuation on the traditional evidence for 

 evolution. In the second lecture the most re- 

 cent work on heredity is dealt with, for only 

 characters that are inherited can become a part 



