94 



D. T. MacDOUGAL 



The decreased swelling in swamp water and the high swelling 

 in bog water were marked and invariable. 



The biocoUoid approaches more nearly to the condition of the 

 protoplast however when in common with all living matter it n- 

 cludes some salts. The above mixture treated with nutrient 

 salts was not available, but some plates in which the oat-protein 

 was replaced by bean-protein to which had been added 0.8% of 

 nutrient salts were swelled in a parallel series. The untreated 

 mixture free from the added salts does not show as high a ca- 

 pacity as that made up with the oat-protein. The measurements 

 of the increase of the agar-bean-protein-salted sections at 15°C. 

 were as follows : 



These measurements were taken at the end of forty hours while 

 some increase was still in progress, but the final relations would 

 not have been materially altered by the use of the end points 

 for the comparisons. The retarding action of the swamp water 

 and the equivalence of swelling in pure water and bog water 

 therefore runs plainly defined through all of the experiments 

 with living and dried sections of plants and in tests with salted 

 and unsalted biocolloids. Calcium nitrate in the concentration 

 used exercises a more marked effect on the salted biocolloid 

 than on the unsalted mixture and on the plant material. The 

 calcium content of the biocolloid is probably much higher than 

 that of the plant so that the two sets of measurements are not 

 strictly comparable. 



The calcium solution contained about eight times as much salt 

 as the bog water and nearly three times as much as the swamp 

 water which also includes a trace of sodium chloride. A series 

 was therefore arranged to compare the action of the two with 

 equivalent salt solutions. Sections of agar and bean-protein 

 impregnated with 0.8% of nutrient salts were swelled at 15°C. 

 with results as follows: 



