MACDOUGAL AND SPOEHR— GROWTH AND IMBIBITION. 345 



The albumen did not exert any important influence on the swell- 

 ing of the mixture until it was present in proportions as great as 25 

 per cent. The action is not marked even in this high proportion. 

 Neither this nor any other combination in which gelatine formed the 

 greater part displayed water relations at all similar to those of 

 the plant. 



Next egg-albumen was added to agar and agar-gelatine mixtures 

 with results as below, a further illustrative test being made of agar- 

 gelatine : 



The addition of ten per cent, of albumen to agar notably reduced 

 the capacity of agar for swelling in acid and alkali, and appeared to 

 increase the amplitude of swelling in distilled water, although the 

 last matter is not entirely clear. The albumen reduced the swelling 

 of a mixture containing twenty-five per cent, of gelatine slightly 

 in acid and in alkali, but the swelling in water was not markedly 

 greater. This preliminary test yielded results which made their 

 extension highly desirable. Chemical analyses of the egg-albumen 

 were not available, and as nothing was known as to the salts or other 

 substances which might be included, it was desirable to secure 

 material of known origin and composition. Arrangements were 

 made with Dr. Isaac F. Harris, of Squibb and Sons Laboratory, 

 New Brunswick, New Jersey, to prepare some albumen from beans 

 (Phaseolns) and from oats (Avcna) to be used in the mixtures. 

 The preparations from Phascolus were available in February, 1917, 

 and the first tests were made with the "protein" extract which con- 

 tained the water soluble salts of the bean and the proteins which 

 were soluble in water containing these salts. 



