MOORE AND KARRER A SUBTERRANEAN ALGAL FLORA ZbO 



The formula undiluted was : 



Ammonium nitrate 5 gm. 



Monobasic potassium phosphate 2 gm. 



Magnesium sulphate 2 gm. 



Calcium chloride 1 gm 



Iron sulphate Trace 



Water 1000 cc. 



The bottles were inoculated in duplicate under sterile con- 

 ditions with about 10 gms. of soil taken from various depths. 

 Every precaution was taken so that the exposed surface was not 

 contaminated with small particles of soil carried down from the 

 upper layers. The spatula by which the samples were taken 

 was sterilized after each inoculation. Checks were run with 

 bottles that were exposed to the air where the inoculations were 

 taken. In order to lessen the amount of evaporation waxed 



placed 



The sand 



slanted in the bottle so that part of it was not submerged, in 

 this way giving various moisture conditions in the culture. The 

 cultures were then placed in cases where they received good light 

 for at least part of the day. The water lost by evaporation was 

 restored from time to time with sterile water. 



In order to compare the algal flora of different regions and 

 soil conditions, 10 different series of bottles were inoculated 

 with soil samples from various parts of the Missouri Botanical 

 Garden, 1 from Woods Hole, Massachusetts, and 3 from the 

 vicinity of Santa Ana, California. The varieties of soil exam- 

 ined were heavy clay, loose clay, sand, sandy alkali, sandy 

 gravel and humus. All subterranean cultures were obtained 

 from places where the soil had not been disturbed for at least 

 a number of years. This precaution was necessary in order that 

 the algal growths obtained would represent those typical of 

 subterranean conditions and not merely recent surface infec- 

 tions. At no time did a single check culture show growth, thus 

 eliminating the possibility of algal infection from the air. 



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