244 The Structure of Protoplasm 



lation on the concrete meaning of the polyrhythmic functioning of 

 protoplasm on a physical or chemical basis, it may be added that the 

 difference in frequency of component rhythms may mean a differ- 

 ence in frequency of the contracting and relaxing rhythm of proto- 

 plasm. 



I wish to express to Professor William Seifriz my sincere appre- 

 ciation of his kindness in extending to me the courtesies of his 

 laboratory. I was encouraged by his constant aid and cooperation 

 during the course of these experiments. I am indebted to Professor 

 Jacob R. Schramm for permission to work in the Botanical Labora- 

 tory of the University of Pennsylvania. Finally, it is my most pleas- 

 ant duty to acknowledge with thanks the aid granted me by Mrs. 

 Curtin Winsor, who graciously made it possible for me to carry out 

 the present work by supporting my research. 



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