90 D. T. MacDOUGAL 



Per liter 

 gram 



Soluble organic matter . 106 



Ash (chiefly CaS04) 0.048 



Total soluble residue . 154 



Reaction neutral 



Swamp water was procured by the kindness of Dr. S. A. 

 Gortner, who obtained a sample from near Anoka, Minnesota, 

 concerning which he says, 



This sample was taken about 20 miles north of Minneapolis m 

 Anoka County, of which three-fourths of the area consists of peat 

 lands. These peat lands are of the grass and sedge formation, the peat 

 being from 4 to 6 inches or more deep, fairly well decomposed and one 

 of the better grades of peat for agricultural purposes in that it con- 

 tains an appreciable amount of lime. I believe that you will find this 

 sample of water perfectly typical of most of the large grass bogs of 

 Minnesota. 



The analysis of this water shows the following: 



Per liter 

 gram 



Soluble organic matter 0.094 



Ash (CaSOi with trace of NaCl) 0. 128 



Total soluble residue 0.222 



Reaction neutral 



The first trials of the action of these waters was made with 

 living material. Circular disks 12 mm. across and of an aver- 

 age thickness of 11 to 13 mm. were cut out from joints of Opuntia 

 discata which had matured at Carmel, California, in the summer 

 of 1917. Trios of these sections were placed in small stender 

 dishes and a triangular sheet of glass was placed over them. 

 The vertical arm of an auxograph was adjusted so that its lower 

 end rested in a ground socket in the center of the glass plate. 

 The pen was adjusted to the zero line of the record sheet and 

 when the dishes which had a capacity of 25 cc. were filled with 

 a solution, the average increase of the thickness of the three 

 sections was recorded. All of the records given in this paper 

 were made with liquids ranging in temperature between 13.5°C. 

 and 15°C. unless otherwise specified. The first set of measure- 

 ments of swelling of Opumia comprises the following data: 



