SOLUTION AND FIXATION OF BIOCOLLOIDS 



131 



WATER 

 DISTILLED 



CITRIC ACID 



O.Olx 



POTASS I M 



111 HI! ATE 

 0.01 M 



POTASSIUM 



NITRATE 



0.01M 



Living median slices 



Firsl swelling. 



11.4% 



0.4% 



6.6% 



9.2% 



Above sections dried. Second swelling calculated on basis of original thickness. 



Second swelling. 



17.5 



26.4 



24.5 



22.4 



The thin slices used to obtain the results in the first line, 

 when dried came down to about one-fourth of their original 

 thickness. To have returned to their original dimensions ex- 

 pansions of about 75 to 85% would have been necessary. The 

 lesser swellings indicate that in the first treatment the sub- 

 stances giving the sections their high imbibition capacity had 

 been largely extracted. 



On the other hand but little material in addition to water is 

 lost in the dehydration of cell masses by simple drying. The 

 reduction amounts to about three-fourths of the total volume 

 and an even greater proportion by weight. The chief interest 

 centers in the disposition of the electrolytes and amino-com- 

 pounds which are combined with the more liquid and more solid 

 phases of the colloid of the active cell. The acids, salts and all 

 substances in solution which do not actually crystallize out in 

 the vacuoles would be finally adsorbed by the colloids in a 

 highly concentrated condition. This would have certain effects 

 inclusive of coagulation which would influence the re-hydration 

 of such cell-masses or material, and which would prevent a 

 return to the original or living condition. 



If now we turn to the swelling of sections dried directly from 

 the living or fresh condition the increases are seen to bring the 

 material back to a volume less than the original in various 

 solutions, the deficit being greatest in the alkali and least 



