PREFACE 



I am greatly indebted to the Trustees of the Abraham Flexner 

 Lectureships of Vanderbilt University Medical School for 

 providing the opportunity for the delivery and publication 

 of these lectures. Their substance represents an attempt at 

 a different type of approach to the theoretical problems of 

 immunity that have fascinated me for many years. To many 

 workers the approach will seem out of key with modern 

 trends to press biochemical concepts to the Umit in the inter- 

 pretation of biological phenomena. To others it may be at- 

 tractive to set aside speculation on matters that are currently 

 inaccessible, in favour of relatively simple morphological and 

 genetic concepts which to a large extent at least are susceptible 

 to experimental test. 



The discussion of immunity has been set between a brief 

 account of clonal phenomena amongst bacteria and viruses 

 on the one hand, and of malignant disease on the other. In 

 this way it was hoped to clarify the unfamiliar use of clonal 

 ideas in discussing mesenchymal cells by a comparison with 

 fields in which such ideas are widely or universally accepted. 

 In the process it became evident that there were many con- 

 ditions in human pathology which are essentially deviations 

 of the immune processes in the direction of malignant change. 

 It may be hoped that the clonal approach will find its 

 most fruitful application in bringing a better understanding 

 of the pathology of these conditions. 



F. M. BURNET 

 NASHVILLE 



May igj8 



IX 



