42 MACDOUGAL-^ACTION OF LIPOIDS IN GROWTH. 



Repetition of these experiments gave no data varying notably 

 from the above. All were carried out at 15° C. 



A fourth plasmatic layer was prepared consisting of agar 5 g., 

 gelatine 2 g., potassium oleate 5 mg., and lecithin 25 mg., and parallel 

 series in potassium and sodium chloride were run at laboratory tem- 

 peratures of 14 to 18° C. with results as follows, in which the total 

 excretions for three cups with each salt are given : 



KCl o.oiM 5.8 c.c. 8.4 c.c. 9.4 c.c. Total in 140 hours 23.2 c.c. 



NaCl o.oiM ...5.2 c.c. 6.7 c.c. 8.2 c.c. " " " " 20.1 c.c. 



It is to be seen that the action of the sodium and potassium salts 

 is most nearly equivalent in gelatine, that the greatest differences are 

 shown in a layer of agar, and agar-gelatine soap where the amount of 

 excretion from a potassium cell may be double that of one filled with 

 sodium. However, when lecithin is incorporated in the mixture, the 

 difference between the action of the two bases is not very great. 



The several processes which are integrated in these results may 

 be simply stated as follows : First, the plasmatic layers begin to go 

 into solution as soon as the cell is filled and the resulting osmotic 

 action will be one characteristic of such solution. About 10 per cent, 

 of an agar-gelatine soap layer 2 or 3 mm. in thickness would be dis- 

 solved at the end of the fourth day, but after this saturation point of 

 the cell contents is reached the plasmatic layer dissolves slowly as new 

 supplies of water are absorbed so that cells have been seen to operate 

 for 60 to 80 days. 



It has been pointed out previously that such a cell with a plasmatic 

 layer of agar-gelatine-potassium oleate mixture has at the beginning 

 a tonicity by which it shows endosmosis in a 0.03M solution of 

 potassium chloride. After some action in this concentration it may 

 be moved by stages to a solution of 0.005M from which it will absorb 

 water.^^ 



11 MacDougal, D. T., " Distentive Agencies in Growth," Proc. Soc. for 

 Exper. Biol, and Med., 18: 103,-110, 1921. 



12 See Fitting, H., " Untersuchungen ueber die Auf nahme von Salzen in 

 die lebende Zelle," Jahrb. f. Wiss. Bot., 56: 1-64, 1915. 



Stiles, M. A., and Kidd, F., " The Comparative Rate of Absorption of 

 Various Salts by Plant Tissue," Proc. Roy. Soc. Land., B, 90, 487-504, 1919. 



Kahho, H., " Kin Beitrag znr Permeabilitat des Pflanzenplasmas fiir die 

 Neutralsalze," Biochem. Zeit., 120, 284-303, 1921. 



