1320 
The results mentioned above would not have been attained, if I had 
not been sustained by the confidence in the success of the undertaking, 
which the director of the Laboratory, Prof. E. Verscaarreit, has 
always shown, and by the aid in word and deed, I experienced from 
Mr. J. VAN DER ZWAAL, instrumentmaker, and Mr. J. Mrssras, clockmaker, 
in the technical execution of the plans. 
October 1920. 
(From the Laboratory of Plant-Physiology 
of the University of Amsterdam). 
