Dedication of Volume to 



Percy W. Zimmerman 



Early in its deliberations, the Organization Committee decided that 

 Percy \V. Zimmerman would be designated as honorary chainnan of 

 the Fourth International Conference on Plant Growth Rearulation. 

 Fate intervened, and this opportunity to provide a small token of 

 honor and appreciation for a lifetime of faithful senice to the study of 

 plant growth was denied. He succumbed to an embolism following an 

 emergency operation at Wenatchee, Washington, on August 14, 1958. 

 The dinner meeting which he was to have addressed during the Confer- 

 ence was changed to a memorial meeting in his honor, and Dr. ^V'. J. 

 Robbins was asked to give the address. 



From Dr. Zimmerman's laboratory, in collaboration with Dr. A. E. 

 Hitchcock, there came an ever-expanding series of discoveries over a 

 period of a quarter of a century. They found the means of using indole- 

 3-butyric acid to root cuttings of species difficult to propagate and dis- 

 covered the growth regidating properties of 2,4-dichlorophenoxyacetic 

 acid, a-naphtlraleneacetic acid, and the halogenated benzoic acids. These 

 and many other similar findings were not fortuitous accidents. They 

 came from prolonged and diligent search that was guided by certain 

 lines of provocative thinking. 



To know "Zim" was to respect him even when you differed with his 

 ideas. He was unflinching in his examination of the validity of every 

 new idea and every piece of data. He insisted on testing new concepts 

 extensively on many kinds of plants under all sorts of conditions before 

 accepting an observation as factual. He was just as relentless in question- 

 ing the ideas of his colleagues in research and administration as he was 

 in scrutinizing his own progress. 



His blunt questioning of all theories that were superficially drafted, 

 or that left unanswered questions, did not necessarily endear him to 

 his colleagues. He believed in the use of theory in the research lal)oi- 

 atory but he was distressed that tenuous theories should be published 

 as semi-facts where they might lead neophytes into the wrong channels 

 of learning. The pages of history show that his skeptical attitude has 

 been vindicated as the auxin a and auxin b concept has been laid to 

 rest, the concept of the ubicjuitous role of "auxin" in all plant functions 

 has been drastically changed, and the superficial theories on the relation 

 of chemical structure to growth regulant aliility of molecules ha\e been 

 disintegrated by wider knowledge. 



Such was the unwavering honesty and loyalty of the man to his 

 dedicated purposes in life. He spent 32 years in the laboratories of the 

 lioyce Th(jnipson Institute, breathing life into its ideal of acquiring use- 

 ful new knowledge on plant life. It was a richer place for having had 

 liini as an associate. The genial smile, the vvarni interest in everything 

 and every person around him, and the ever youthful aj^proach and un- 



