Duggar — Relation of Marina Algae to Salt Solutions. 475 



into consideration electrolytic dissociation.* t (H). In each 

 case a stronger solution of KNO3 is required than of NaCl. 

 In strong solutions, such as are here employed, the degree of 

 dissociation might be about six per cent greater in the NaCl 

 than in an equivalent KNO3 solution in distilled water. On 

 the other hand, in sea water there is already present a con- 

 siderable amount of NaCl and of other chlorides, all of which 

 would diminish the dissociation of the NaCl added, and con- 

 sequently tend to balance up the iouic relationship. The 

 conditions, are, however, complex in such mixed solutions, 

 and other factors may be important. (HI). If now the iso- 

 tonic value of sea water, .6 N KNO3, as assumed, be added 

 in the columns giving the results of these solutions in sea 

 water, an interesting comparison is found between these com- 

 puted values and the experimental values in distilled water, as 

 compared below. 



Table II. 



Practically the same osmotic pressures are found for the 

 algal cell whether the determination is made in pure NaCl so- 

 lution or in NaCl in sea water. When the case is KNO3 

 in sea water the point of phismolysis is determined as begin- 

 ning at a concentration from 2-6 per cent higher than in the 

 corresponding test with NaCl ; and the point of plasmolysis 

 in pure KNO3 solution is at a strength from 20-42 per cent 

 above that of KNO3 in sea water. In the case of sugar, the 



* Von Rjssleberghe, Fr. — Reaction osmotique des ("elluUs Veg6talt;s 4 

 la conceutratiou du Milieu. Extrait, M^moire.s couronu^s et autres M6m. 

 publ. p£.r I'Acad^mie ruyale de Belgique. T. 68. 1899. p. 104. 



t Livingstone, B. E.— The Role of Diffusion and Osmotic Pressure in 

 Plants. Chicago, 1903. 



