The American Society of Plant Physiologists wishes to show its 

 respect for the late Professor Herbert Freundlich by publishing 

 his portrait as a frontispiece to his chapter in this Monograph. The 

 article on Thixotropy which follows was the last manuscript writ- 

 ten by Professor Freundlich. Rare was the contribution from 

 Professor Freundlich's laboratory which did not enrich physiology 

 as much as it did chemistry, and none had a greater influence on 

 biological thought than did thixotropy. 



Those who knew Professor Freundlich will remember him for 

 his intense interest in biology and his broad understanding of it. 

 Those few among us who had the good fortune to work in his 

 laboratory will remember him as one of the most inspiring teachers, 

 fair and tolerant colleagues, and gracious companions that a man 

 could desire. His was a truly great character. Biology has lost 

 one of its ablest and noblest friends. 



[83] 



