A COMPARATIVE STUDY OF PERMEABILITY IN PLANTS. 



By W. J. V. OSTERHOUT. 



{From the Laboratory of Plant Physiology, Harvard University, Cambridge) 



(Received for pi;blication, October 28, 1918.) 



The writer has arrived at certain general conclusions concerning 

 the behavior of protoplasm, which are based largely on the study of a 

 single plant. To ascertain whether they have general validity it is 

 necessary to study other plants as well as animals. The following 

 paper gives a brief resume of results obtained with a red alga (Rhody- 

 menia palmata), a green alga {Uha rigida), and a flowering plant 

 (Zostera marina) . These forms were chosen because they differ greatly 

 from the brown alga Laminaria Agardhii (which furnished the material 

 for the experiments hitherto described) , not only in the chemical com- 

 position of the cell walP but also in the structure of their tissues. 



The experiments on Laminaria were made by cutting disks from 

 the fronds and packing them in a cylinder, the electrical resistance 

 of which was determined as previously described.^ 



The experiments with Rhodymenia palmata (the common dulse of 

 the Atlantic coast) were carried out in precisely the same manner as 

 those on Laminaria. This was possible because Rhodymenia forms 

 thin sheets of tissue, large enough to be cut by a cork borer into 

 disks 13 mm. in diameter. The disks were packed together, like a 

 roll of coins, to form a cylinder, the electrical conductivity of which 

 was measured as previously described.^ Rhodymenia is much more 

 difficult to keep in good condition than Laminaria, and on this ac- 

 count is not so well suited to investigations of this kind. It de- 

 mands a low temperature and thorough aeration, and even with these 

 does not live so long as Laminaria. 



^ Regarding the composition of the cell wall in algas see Czapek, F., Bio- 

 chemie der Pflanzen, Jena, 2nd edition, 1913, i, 640 £f. 

 2 Osterhout, W. J. V., /. Biol. Chem., 1918, xxxvi, 557. 



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