Water Deficit or Unsatisfied Hydration Capacity. 103 



of its volume by boiling, spores immersed in the concentrate plasmo- 

 lyzed, as might be expected. The temperature implied would of course 

 cause many changes in the constitution of the sap. The fresh juice 

 was seen to cause plasmolysis in vegetative cells of Spirogyra setiformis. 1 



In any consideration of the general facts which are brought into a 

 discussion of permeability in the experimental laboratory, one of the 

 most disturbing features is the frequency with which results are en- 

 countered which can not be duplicated. The effects of phlorizin on 

 the diffusion of sugar is an example of such a matter. Preparations 

 of the fresh and turgid inner layers of onions prepared by Dr. H. A. 

 Spoehr were found to contain an amount of sugar suitable for experi- 

 mentation, and when such sections were placed in distilled water for 

 a short period the amount of sugar extracted was fairly equivalent 

 to that coming out of other sections placed in the solution of potas- 

 sium carbonate and phlorizin (0.02 M) customarily employed in the 

 experiments with this glucoside, and also to the amount of sugar 

 which was found to diffuse out of sections placed in the potassium- 

 carbonate solution alone. Wachter believed he had proved that the 

 addition of a trace of potassium salt to water would prevent the 

 diffusion of sugar from- tissue of onions. 2 



Sections of the layers of onion bulbs were placed in distilled water 

 and in solutions of phlorizin and potassium carbonate, to ascertain 

 to what relative extent they might influence hydration. Trios of sec- 

 tions having an average thickness of about 2.3 mm. were prepared 

 for measurement under the auxograph and a series of three prepara- 

 tions were swelled at 20 C. The set in water increased 1.5 per cent, 

 that in the potassium carbonate 4.3 per cent, and the one in potas- 

 sium carbonate and phlorizin 9 per cent, the maximum amount. 



In the repetition of the above with other material the results were 

 somewhat different. It was found that trios at 20 C. swelled 4 to 8 

 per cent in water, 7 to 11 per cent in the potassium-carbonate solutions, 

 and between 5 and 6 per cent in the solution of phlorizin and potas- 

 sium carbonate. Such results are indicative of an inequality of the 

 material, but it is evident that not only does potassium carbonate 

 not prevent the diffusion of sugar from the onion, but that a hydra- 

 tion of greater amount may occur in its presence than in water alone. 

 Nothing could be determined as to the action of the phlorizin on plant 

 colloids with relation to sugar. 3 



It has also been found impossible to bring the results of theoretical 

 antagonisms of substances taken up by protoplasm into harmony 

 with the results of hydrations made in the present connection, a matter 



1 Kunkel, Louis Otto. A study of the problem of water absorption. 23d Ann. Rep. Missouri 

 Botanical Garden, pp. 26-40. 1912. 



* Wachter, W. Untersuchungen ileber den Austritt von Zucker aus den Zellen der Speicher- 

 organe von Allium cepa und Beta vulgaris. Jahrb. f. wiss. Bot., 41: 165. 1905. 



3 See Brooks, S. C. Permeability of cell-walls of Allium. Bot. Gaz., 64:509. 1917. 



