DEPARTMENT OF BOTANICAL RESEARCH. 



61 



features of a colloidal mass on its swelling reactions. The colloids in 

 question are poured on glass, gold-foil, or filter-paper in a layer 0.8 mm. 

 in thickness, and are prevented from shrinking superficially while 

 coming down to a thickness of 0.11 to 0.2 mm. The result is a definite 

 structure and a capacity for swelling determined by the conditions of 



Percentage of swelling of biocolloids at 15° C. in water, acids, hydroxides, and potassium 



nitrate at 0.01 M. 



Parts. 



KOH, 

 pH = 11.99. 



NH4OH. 

 pH = 10.61 



KNO3, 

 pH=6.6. 



HNO3, 

 pH=2.01. 



HCl, 

 pH=2.01. 



Water. 



Agar 



Soy albumin . . . 

 O.ll mm. 



Agar 



Opiintia mucilage 

 Soy albumin. . 

 0.14 mm. 



Agar 



Cherry gum 



Soy albumin . . . . 

 0.17 mm. 



Agar 



Acacia 



Soy albumin . 

 0.16 mm. 



Agar 



Acacia 



Gelatine . . . 

 0.19 mm. 



Agar 



0.16 mm. 



Gelatine 



0.25 mm. 

 Thickness. 

 Volume. . . 



8 6.5 

 2 6.2 



4 6.5 

 4 5.8 

 2 6.2 



4 6.5 

 4 5.1 

 2 6.2 



4 6.5 

 4 5.1 

 2 6.2 



4 6.5 

 4 6.2 

 2 5.2 



6.4 



5.2 



1,000 



530 



700 



700 



1,200 



844 



1,640 

 3,190 



910 



700 



1,000 



r50 



1,000 



1,000 



1,560 

 3,090 



910 



1,310 



1,400 



1,400 



1,060 



2,000 



640 



600 



650 



650 



525 



1,060 



455 



440 



685 



600 



525 



970 



875 

 1,246 



2,040 

 3,852 



1,960 

 4,700 



2,000 



2,785 



2,415 



2,100 



2,000 



3,700 

 4,200 



960 

 1,570 



dehydration. Thus sections of agar and cherry gum, which swelled 

 2,400 per cent in thickness, extended only 4 per cent or less in water. 

 Such action is not to be predicated of all colloids. 



Gelatine plates prepared as above seem to take on a modification 

 of this heterotropic structure. The increase in the length and width 

 of a small section of such plates may be from 40 to 80 per cent or ten 

 times as much as that of agar-cherry gum, yet it is not more than one 

 fortieth or fiftieth of the expansion in thickness. This action may well 

 be suggested as the physical basis of cytological performances in the 

 plant cell. 



