22 LABORATORY BACTERIOLOGY. 



EXEECISE XV. 



THE INFLUENCE OF DEXTROSE ON THE FORMATION OF CAR- 

 BON DIOXID AND AMMONIA FROM DRIED BLOOD. 



1. Weigh off eight 100 gram portions of air-dry, sieved 

 soil, in tumblers. 



2. Arrange series under bell-jars as in preceding exer- 

 cises as follows: 



1 & 2 — no soil. 

 3 & 4 — 100 grams of soil. 



5 & 6 — 100 grams of soil -|- 5 grams dried blood. 

 7 & 8—100 grams of soil -f- 3 grams dextrose. 

 9 & 10 — 100 grams of soil -f- 5 grams dried blood -f- 

 3 grams dextrose. 



3. Stir thoroughly; increase soil moisture to optimum 

 by the addition of sterile water; use 12 cc. additional for 

 the dried blood and 7 cc. for the dextrose. 



4. Titrate daily the barium hydrate solutions and re- 

 place by fresh portions for six consecutive days. 



5. At the end of six days transfer the soil portions to 

 copper flasks; add water and magnesium oxid; distil and 

 titrate. 



6. Calculate rate of decomposition of the dried blood, as 

 influenced by the dextrose. 



