34 MACDOUGAI^ACTION OF LIPOIDS IN GROWTH. 



3. The use of saponin or solutions which liquefy or displace 

 lecithin in the cell contents or external layer increases permeability, 

 presumably by increasing hydration, and lessens osmotic action. This 

 is in agreement with the results of Boas and Kahho. 



4. The nature of the action of saponin on artificial cells suggests 

 that this substance affects the permeability of the outer clay walls of 

 artificial cells. The hydration reactions of living and dead cell- 

 masses measured with the auxograph show a similar influence on the 

 wall of the plant cell. 



5. Dried plates of biocolloids which show many similarities in 

 hydration to the action of protoplasm, but which contain no lipoid, 

 are rendered less permeable when swelled in a saponin solution. Such 

 a solution increases the permeability of plant cells. The results sup- 

 port the inference that this effect is due to the action of the solution 

 upon the lipoid constituent.^ 



6. The artificial cell as used in the experiments shows accelerated 

 action when a lipoidal layer is deposited between the plasmatic jelly 

 and the outer clay wall. With cell-contents of NaCl o.oiM im- 

 mersed in CaClo 0.00 lilf, negative osmose, then positive osmose, oc- 

 curs. The tonicity of the cell may be seen to increase from 0.003 ^*^ 

 .005M KCl. The "life" or period of activity of such a cell may 

 extend over a period of 60 to 80 days with renewal of the immersion 

 liquid, but not of the cell-contents. Anomalous osmose may be ex- 

 hibited by the outer wall, which is semi-permeable to sugar, asparagin, 

 and other organic substances, but the action of the cell when the 

 plasmatic layer is added is positive. 



7. Living cell-masses which show a water deficit or a hydration 

 capacity of 40 per cent, and which remain turgid when swollen take 

 up only about one fourth of this amount of water when increased 

 permeability sets up shrinkage in saponin o.ooc,M. The effect of the 

 saponin decreases with the concentration to a minimum at about 

 0.0002M. 



8. The effect of the saponin upon permeability as measured by the 

 swelling which ensues before shrinkage begins is not definitely accel- 



1 Quincke, G., Ann. d. Physik u. C hemic, N. R, 35, 580, 1888. Overton, 

 E., " Osmotische Eigenschaften," Vierteljahrsschr. Naturforsch. Ges., Zurich, 

 40, I, 1895. See also " Ueber die allegemeinen osmotischen Eigenschaften d. 

 Zelle" by this author in the same publication, 44, no, 1899. 



