298 Dandeno : Osmotic theories 



ments against the gas-pressure theory are: (i) Morse's experi- 

 ments with sugar solutions show an osmotic pressure of about 32 

 atmospheres in a gram-molecular weight per liter solution, when 

 it should, by van't Hoff's law, be only 22.4 or thereabouts. (2) 

 The writer's own experiments with colored solutions of various 

 kinds and with different solvents, also his physiological experi- 

 ments concerned with absorption and with cell sap. (3) Oster- 

 hout's experiments on plasmolysis. (4) Many operations connected 

 with living plants, e, g.^ the formation of ice (in freezing w^eather) 

 in the intercellular spaces, the formation of calcium oxalate crys- 

 tals outside the living cells, and others. (5) The growth of the 

 Traube pellicle. (6) Kahlenberg's experiments and discussions. 

 The Attraction Theory here proposed is not only in harmony 

 with all the phenomena presented as argument against the gas- 

 pressure theory, but it affords a reasonable explanation in each 

 and every case. This theory is not claimed to be entirely new, 

 for it was used, in part here and there, many years ago, but was 

 never applied generally enough, hence it was not surprising to 

 find van't Hoff's law superseding. But van't Hoff's law shows so 

 many weak points that it cannot be accepted as explanatory of 

 osmotic pressure, 



Michigan State Agricultural College, 

 East Lansing, Michigan. 



