34 



Hydration and Growth. 



When such material is stirred into distilled water a clear solution is 

 obtained. The mixture was added to the melted agar at about 30 C. 

 An amount of lecithin (Merck) from eggs, supposed to be about a gram, 

 was smeared on the outer wall of a thin vial. The vial was dropped 

 into the warm mixture and shaken until it had nearly all passed into 



TABLE 16. 



the solution, giving it a brownish tinge. By another method the 

 lecithin was smeared on the inner surface of a warmed flask. The 

 agar-protein mixture was poured in at a temperature of about 45 to 

 50 C. and shaken until all of the lecithin had been taken up. Dried 

 plates prepared in this way showed no important departure from the 

 behavior of mixture without lecithin. A series of such swellings with 

 a plate 0.47 mm. in thickness at 16 to 18 C. gave the following: 



TABLE 17. 



Water 



Citric acid, 0.01 N 



Sodium hydroxid, 0.01 M . 



p. ct. 



1,106 

 329 

 436 



It is obvious that these crude tests by no means constitute an ade- 

 quate trial of the effects of fats or lipins in hydration of living matter. 

 The prominence of the lipoid theory of the cell-membrane and the 

 weight of some of the arguments adduced in its support renders it 

 highly important that refined methods of experimentation be used in 

 incorporating a lipin colloid in pentosan-protein mixtures, the hydration 

 of which might yield results of importance bearing on permeability. 



In an effort to make a mixture bearing a closer resemblance to the 

 general hydration relations of plant protoplasm, the following mate- 

 rials were assembled: 



Agar 4.2 grams, which was liquefied in 160 c.c. of water at tempera- 

 tures of about 100 C., oat protein 0.18 gram, and oat albumin 0.820 

 gram, were dissolved by shaking up with 50 c.c. cold water. After this 

 had been done 0.2 gram of lanolin was put in a vessel with the dis- 

 solved albumin and warmed to about 35 C., being shaken vigorously 

 at intervals. The agar was now strained through two layers of cheese 

 cloth into a beaker and stirred until it came down to a temperature of 

 about 40 C., when it was placed in an enameled cup suitable for the 



