Effed of Salts and Acids on Biocolloids and CeU-masses. 



Dried plates were made up in the usual manner and freed from 

 water in a special chamber with fan at a temperature of about 16° C. 

 Swellings at 14° to 17° C. were as shown in table 42. 



Table 42. p. ci. p. ct. 



Distilled water 2,200 2,240 



Citric acid 0.01 N 802 880 



Sodium hydrate, 0. 01 M 602 680 



Potassium chloride, hydrochloric acid, 0.01 M 700 640 



The notable feature is the high swelling in water and the fact that 

 the increase in the acid solution is less than in the alkaline, facts 

 which are probably due in part to the action of gum acacia. This 

 set of swellings has unusual interest because of its composition, in 

 which the categories of substances in the plant are represented with 

 some fairness and adequacy (fig. 9). fig. 9. 



Tracing of auxographic 

 records of swelling of 

 sections of plates 

 consisting of 6 parts 

 agar, 2 parts gum ar- 

 able, 1 part gelatine, 

 1 of bean albumin 

 and .05 nutrient salts 

 in water. A, citric 

 acid .01 N. £,sodium 

 hydrate. 01 M. C, po- 

 tassium chloride and 

 hydrochloric acid 

 .01 M. D, at 14° to 

 17° C. Downward 

 course of pen tracing 

 denotes increase as 

 indicated by numer- 

 als on margin. 



The results obtained in some of the foregoing experiments indicated 

 that the treatment of the biocoUoid with salts before acid solutions 

 were applied might show some features of importance, and this was 

 also supported by the alternating effects described in detail elsewhere 

 in this volume. Plates had been made of agar 90 parts and bean 

 protein 10 parts in two sets. In one a culture solution was used in 

 such concentration that the included salts formed 0.85 per cent of the 

 dry weight of the sections. In the other the concentration of the 

 salts was about ten times this amount. Both showed opaque dots or 

 minute regions, supposedly insoluble globulin. 



Swellings were made at temperatures of 16° to 17° C. on October 12 

 and 13, 1917, and the measurements obtained from the sections con- 

 taining the larger proportion of salts are as given in table 43. 



Table 43. 



p. ct. 



Distilled water 522 



Qitrio acid, 0.05 N S83 



Citric acid, 0.05 N 413 



Citric acid, 0.0005N 348 



Citric acid, 0.00005N 500 



