230 Puget Sound Marine Sta. Pub. Vol. 1, No. 21 



changes the permeability so there will be exosmosis, the reaction will not 

 be within the cell. This may explain why few crystals are formed within 

 the cell in the reactions for potassium and sodium. Czapek^ has stated 

 that ionization is a factor. However it is not certain whether all reactions 

 must be ionic. 



If the percentages of the inorganic constituents in the cell are com- 

 jDared with those of sea-water, it is readily seen that the nature of the 

 salts depends upon the selective absorption of the protoplast. The pro- 

 portions within the cell are quite different from those in solution in the 

 sea-water. The dissolved solids in sea-water are given as ions in the 

 following,: Na, 30.64% ; Mg, 3.76% ; Ca, 1.20% ; K, 1.09% ; CI, 55.21% ; 

 SO,, 7.70%; CO3, .21%; Br, .19%.« 



The percentage of sodium in sea-water is about thirty times that of 

 potassium, but the quantity of potassium in the cell far exceeds that of 

 sodium. Again, iodine is present in sea-water in such small quantities that 

 it can hardly be detected, yet it can easily be detected in the cell. 



This large percentage of potassium may have some significance. It 

 has been found to be essential in plant -growth and metabolism. In meta- 

 bolism it has been connected with the formation of carbohydrates and 

 proteins.^ Schimper^° showed that potassium was essential to the forma- 

 tion of the primordia of organs and that within certain limits the size 

 depended upon the amount present. Although it was not possible to test 

 the amount of potassium present in the actively growing region of the stipe 

 and fronds, it may be a factor in determining the size of the plant. 



CELL WALL 



In general the composition of the cell walls of the algae is uncer- 

 tain. In a large number of cases the basic substance seems to be cellu- 

 lose, but there are other substances present that do not respond to the 

 ordinary cellulose reactions. 



In the Cyanophyceae the presence of cellulose is uncertain. ^^ Ac- 

 cording to Gomont^^ and others the walls in general are resistant to acids, 

 copperoxyammonium and iodine. Lemaire,^^ using color reactions, called 

 the gelatinous material in the cell walls of Nostoc, Gloeocapsa and similar 

 algae a pectin substance. Virieux^^ found callose in the Cyanophyceae. 



In the green algae the cell walls have been found microchemically to 

 be of cellulose, corresponding to the cell walls in the parenchyma tissue 

 of higher plants. The products of hydrolysis, however, differ ; for instance, 



7Czapek, F. Chemical Phenomona in Life, p. 74. New York. 1911. 

 sMurray, J., and Hjort, J. The Depths of the Ocean, p. 176. London. 1912. 

 oDuggar, B. M. Plant Physiology. 172. New York. 1913. 

 lOJost, L. Plant Physiology. Eng. Ed., p. 84. Jena. 1907. 

 iiCzapek, P. Biochemie der Pflanzen; 2nd ed. 1:640. Jena. 1913. 

 i2Gomont, Bull. Soc. Bot. 35: 1888. 

 isLemaire, A. Journ. de Bot. 15:302. 1910. 

 i4Virieux, J. Compt. rend. 151:334. 1910. 



