EFFECT OF BOG AND SWAMP WATERS ON SWELLING 

 IN PLANTS AND IN BIOCOLLOIDSi 



D. T. MacDOUGAL 



Desert Laboratory, Tucson, Arizona 



Direct effects of the waters of bogs and swamps in producing 

 modifications of growth, departures in structure and form and 

 in influencing general nutrition are well established and have 

 long been known. The numerous analyses of the water have 

 failed to disclose physico-chemical features which might be 

 held responsible for the very direct and positive action exer- 

 cised in the determination of the plant formations of such 

 places. The history of such attempts is a long one and need not 

 be rehearsed here, as this was admirably done at the San Diego 

 meeting of this Society. ^ The most recent contribution to the 

 subject is that by Clements who found that some of the effects 

 of bog water disappeared with its oxygenation. 



One need not go very far into the main problem to be made to 

 realize that many of the unsolved questions are not to be attrib- 

 uted to a lack of knowledge of the composition and properties 

 of the waters, but to a failure to understand certain features in 

 nutritional physiology and growth, notably the water-relations. 

 The present paper includes the results of some studies in imbi- 

 bition which were undertaken primarily for the purpose of deter- 

 mination of the principal physical factors in growth but which 

 have been extended to a general consideration of swelling in 

 protoplasm as affected by its own composition and by various 

 solutions. 



In the effort to analyze growth and to identify some of its 

 more important constituent processes it was reasoned that if the 



1 Presented at the meeting of the Ecological Society of America, Pittsburg, 

 Jan. 1, 1918. 



2 See Rigg. Summary of bog theories. Plant World, 19: 310. 1916. 



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