SECTION VI 



RELATION OF MICROORGANISMS TO THE PHYSICAL 

 PROPERTIES OF SOIL 



Exercise i 

 Movements of Soil Water 



1. PREPARE four glass cylinders or large test-tubes as 

 follows: Fill two three-fourths full of quartz sand and 

 two three-fourths full of soil. 



2. Treat as follows: 



(a) Sand plus i per cent, of sugar bouillon previously inoculated with 



5 c.c. of a rich soil suspension. 

 (6) Sand plus i per cent, of sugar bouillon previously inoculated with 



5 c.c. of a rich soil suspension. 



(c) Soil plus i per cent, sugar. 



(d) Soil plus i per cent, sugar. 



3. Add enough bouillon to the sand and enough water to 

 the soil to completely saturate the columns. 



4. In order to prevent bacterial growth add 5 c.c. of 

 a i : 5 mercuric chlorid solution to cylinders (a) and (c), 

 and the same amount of water to cylinders (b) and (d). 



5. Mark on the cylinders the height of the column of 

 water. 



6. Incubate at 28 C., and examine each day. 



