ON BICOLLOIDS AND CELL MASSES. 



23 



Plate A with which the salt tests described in the previous pages 

 were made. With reference to the hydrogen ion concentration the 

 solution of salts added to the agar had a PH value of about 5.8 to 

 6, the agar alone being about 6.5. 



The salted agar showed a swelling in even the attenuated solu- 

 tions of calcium and magnesium chloride less than in water. Such 

 solutions accelerate swelling in pure agar. The swelling of the 

 salted agar in sodium solution was as 102 with water at 100, while 

 that in the potassium solution was 132. That this inequality is not 

 simply a matter of hydrogen ion concentration is evinced by the 

 fact that the sv/elling in the acid at PH 4.2 was practically equiva- 

 lent to that of the potassium chloride at 5.7. 



The incorporated solution may be regarded as approximately 

 balanced and when the sections were swelled in a similar solution 

 the maximum of the series was reached, the increase being as 150 

 to water as 100. 



An identical solution was used in making up " Bacto-gelatine "' 

 and the results of the hydration of sections of the dried plates are 

 as in Table VH. 



Hydration of gelatine plate made up gelatine 5 g., 10 c.c. KCI 

 at 0.01 M, 6 c.c. NaCl at o.ooi M, and CaCU 10 c.c. at o.oooi M, 

 and water 25 c.c. at 14° C. Sections 0.24 to 0.26 mm. in thickness. 



TABLE VIL 



It is to be recalled that this gelatine had a Ph value of 5.2 and 

 that the incorporated salts a Pli of about 5.8 to 6, so that when the 

 dried sections were placed in a salt solution of this constitution the 

 swelling was less than in water and that a similar decrease was 

 noted in the calcium and potassium solutions in 0.0001 M and o.ooi 

 M solutions and in the calcium solution at o.oi M also. Increases 



