viii PREFACE 



volume are not included here, but will be published 

 elsewhere. Our difficulties and the shortcomings in 

 our argument will be obvious enough even when 

 relieved from references to a massive literature. 



The work of the laboratory, which since the be- 

 ginning of the research has included some 2500 

 experiments, has as far as possible been checked and 

 illuminated at every step by the clinical observations 

 made by my associates, Dr. Lower and Dr. Sloan, 

 and by myself. 



The result of this research, as here presented, is 

 the combined outcome of a large amount of work 

 and enthusiasm on the part of many associates. It 

 represents a generous contribution, not only of labor, 

 but of valuable suggestion and criticism from col- 

 leagues and friends, to whom I wish here to express 

 my gratitude. 



I am deeply sensible of my obligations to Sir Vic- 

 tor Horsley for the opportunity of beginning this 

 research in his laboratory in 1895; and for many 

 valuable suggestions and criticisms ; to Professor 

 Sherrington for reading the original manuscript on 

 " Phylogenetic Association"; and to Professors G. N. 

 Stewart, W. T. Howard, T. Sollman, and J. J. R. 

 MacLeod of the Western Reserve Medical School, all 

 of whom have generously given me the benefit of 

 their wide experience and scientific knowledge. 



To the following laboratory and clinical associates 

 I acknowledge my gratitude and indebtedness for 

 assuming much of the burden of experimental de- 

 tails : Dr. Guy H. Fitzgerald, Dr. A. Cudell, Dr. Homer 

 H. Heath, Dr. C. H. Lenhart, Dr. Worth Brown, Dr. 



