ON BICOLLOIDS AND CELL MASSES. 



17 



thickness and 3 per cent, in length. Increases in thickness and vol- 

 ume of sections of the two plates at 14-15° C. are given below. The 

 agar used was of a specially purified lot which had been freed from 

 salts and diffusible carbohydrates by dialysis, and a thin solution 

 was sprayed into 10 times its volume of neutral acetone. The re- 

 sulting fine shreds were subsequently extracted with hot absolute 

 acetone, absolute alcohol and absolute ether. 



TABLE L 



Th. Vol. Th. Vol. ; Th. Vol. Th. Vol 



Water 



KOH 



HCl . 



KCl . 



NaCl 



MgCb 



CaCh 



1,460 

 71S 



1,140 



1,000 



750 



640 



1,610 1,740 



635! 55"^ 



— j 760 



1,30s 1,420 



1,14s 1,160 



824! 7S0 

 705i 725 



1.990 

 6os|i,570 

 88oj — 

 1.56S1I.570 

 1.32s 1.355 

 824 1,100 

 S3O1 900 



1,7001 



— ji.630 

 1,730.2,500 



I,S2o'2,300 



i,34o[i,470 

 94511,100 



1,800 

 2,800 

 2,680 

 1,590 



o.oooi M. 



Th. I Vol. 



Th. Vol 



— 2,260 2,540 

 1,720 2,000 2,400 2,64s 



1,750 2,040 2,700 2,975 

 1,630 1,925:2,10012,315 



1, 19O1 1, 500,1,75 1 1,95012,160 



The accelerating effect of the potassium hydroxide in its weak- 

 est, and its retarding effect at its strongest concentrations, confirms 

 previous results by Spoehr and MacDougal. This maximum effect 

 is in a o.ooi M solution with a Ph value of 11. A lesser swelling 

 takes place in either a weaker or a stronger solution. 



If we now pass to the acid reactions it will be seen that in HCl 

 at O.OOI A^ with a Ph value of 3 the swelling of the agar is little short 

 of that in water. At some point between this concentration and 

 0.0001 A'' swelling becomes equivalent to that which might take place 

 in water and at the last named concentration with a Ph value of 4.2 

 the hydration is much in excess of that in water, being as 128 with 

 that in water taken as 100. 



The purified agar used has a Ph value of 6.5 when made up at 

 0.75 per cent., which is near the limit of its gelation at 15° C. in the 



5 MacDougal, D. T., and H. A. Spoehr, " Hydration Effects of Amino- 

 compounds," Proc. Soc. Exp. Biol, and Med.. 17: 33-36, 1919. "The Com- 

 ponents and Colloidal Behavior of Plant' Protoplasm," Proc. Amer. Phil. 

 Soc, 59, No. I, 150, 1920. " Swelling of Agar in Solutions of Amino Acids 

 and Related Compounds," Bot. Gac, 70: 268-278, 1920. 



