. AUTHOR'S PREFACE. 



"I ^ his work liurs earned out i/i the Depai-tiiieiit for Rxperi- 

 iJieiital Sin]<^eiy of The Roeke feller htstitute in New York 

 1(^20 — 22, and continued in The Institute for Goieral Patholo<j;v 

 of the University of Uopoihaoen. 



I zvish to acknozvledge my gratitude to the director of the 

 laboratories of The Rockefeller Institute. T)r. Simon F I e x )i e r, 

 for his aid and hospitality during my stay at The Institute, 

 a)id / wish to express my great indebtedness and high esteem 

 to the C hief of 'The Department for Experimental Surgery of 

 The Rockefeller Institute. Dr. Alexis Uarrel, ivhose incentive, 

 broad scientific viezvs I shall always admire. 



Likezvise I zuish to express my great appreciation to the 

 Director of the Institute for General Pathology of the L'^niversity 

 of Uopenhagen. Prof. Dr. 01 uf Thomsen for his kindness 

 and assistance, Z\.'hieh made it possible for me to continue the 

 zvork under such good conditions at a time zvhen, for scientific 

 research in general, these zvere not of the most favourable. 



Copenhagen, Marts sg2j. 



A. F. 



