DAVID NACHMANSOHN AND IRWIN B. WILSON 



1846 Johannes Mueller made the statement that we would 

 never be able to measure the speed with which nerve impulses 

 are conducted. Six years later Helmholtz succeeded in doing it 

 with a most simple technique. History has shown too often 

 that the human mind may cross barriers which appear 

 insurmountable. The ultimate aim of biology to explain 

 phenomena of life in terms of molecular dynamics as 

 postulated by Frederick G. Hopkins (13) in his famous 

 lecture "Some Chemical Aspects of Life" seems today with- 

 in our reach. Vitalism in its various modifications, still 

 vigorously supported in the early part of this century, has 

 practically vanished and very few scientists will deny the pos- 

 sibility of explaining eventually life processes by physicochemical 

 forces. Progress in all fields proceeds, however, at such an as- 

 tonishing pace that it is not easy to grasp the implications even 

 in a single field. This may explain some of the difficulties 

 which have to be overcome if progress in different fields is to be 

 integrated. For the understanding of the living cell advances 

 in the borderline between physics, chemistry, and ultrastructure 

 are essential. Just there the difference in approach and way of 

 thinking makes communication between the various fields of 

 endeavour sometimes difficult. Here the human element, 

 intuition and ingenuity will play a decisive role. Selection of 

 the right material, proper arrangement of experimental con- 

 ditions, judgment and critical appraisal, and above all imagina- 

 tion and boldness of concepts must be combined in order to over- 

 come the difficulties. In looking back at the amazing changes 

 of the last three decades, the hope seems more than ever justified 

 that we will be able to bridge the gaps between metabolism and 

 function, between molecular dynamics observed in vitro and the 

 same reaction occurring within a special and elaborate struc- 

 tural organization of living cells and tissues. 



This article is dedicated to Dr. Hans T. Clarke, Professor of Biochem- 

 istry at the College of Physicians and Surgeons, Columbia University, on the 

 occasion of his retirement as Chairman of the Department. The authors 

 want to express their deep affection for him and their gratitude for his in- 

 valuable guidance, inspiration, and encouragement. 



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