THE RELATION OF CERTAIN MARINE ALGAE TO 

 VARIOUS SALT SOLUTIONS.*! 



B. M. DUGGAR. 



Plasmolytic Stddies4 — Upon beginning some work on 

 the relations of certain marine algae to solutions I attempted, 

 tn March, 1900, to make some measurements of the osmotic 

 pressures in the cells of certain marine algae common at 

 Naples. Solutions of dry potassium nitrate, sodium chloride 

 and cane sugar were prepared in distilled water and in sea water. 

 In the latter solvent the stock solutions were made up as gram 

 equivalent (N) solutions, and with the former solvent they were 

 made up as double normal solutions. Preliminary experiments 

 with each alga used were then made in order to ascertain ap- 

 proximately the strength of the solutions required to give 

 plasmolysis. After these approximations had been obtained, 

 careful dilutions were prepared, each higher concentration 

 differing from the next lower by .01 N. The algae used were 

 carefully examined, and only those which seemed perfectly 

 healthy and normal were employed. In every case the sur- 

 plus sea water was quickly absorbed by means of filter paper 

 from the bits of algae used, and the algae were then momen- 

 tarily washed in a solution of the same strength of salt as 

 that used in the particular experiment under way. A portion 



♦ Presented by title t > The Academy of Science of St. Louis, November 

 6, 1906. 



t Contributions No. 14 from the Botanical Department of the Univer- 

 sity of Missouri. 



X This work was bagaa while occupying the table of the Smithsonian 

 Institution at the Marine Biological Laboratory, Naples, during March, 1900; 

 and further experiments were made at the Marine Biological Laboratory, 

 Woods Hole, in July, 1901. Final experiments upon which this preliminary 

 report is based, were made at the Zoological Station of the University of 

 Montpelier, at Cette, during a short stay in the winter of 1906. The writer 

 is indebted to many members of the scientific staffs of these institutions 

 and to Prof. Chas. Flahault of the Botanical Institute, University of Mont- 

 pelier, for the necessary facilities. 



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