358 
IOWA ACADEMY OF SCIENCE Vor. XXIX, 1922 
CLASSIFICATION 
DIGESTION : — Largely hydrolytic, rendering soluble insoluble 
compounds. Primarily extracellular. Slight changes in energy 
relationships. May be anaerobic or aerobic. 
Carbon: — hydrolytic splitting, (the hydrolysis of starch) no 
designation of the bacterial action involved. 
Nitrogen : — splitting of higher nitrogen-containing compounds 
with the formation of peptoses, peptids, peptones, amino 
acids and ammonia as end products. 
Bacterial term — ammonification. 
Sulfur : — splitting of organic sulfur compounds with the for- 
mation of hydrogen sulfide as the end product. 
No designation of bacterial action involved. 
ASSIMILATION : — Elements or compounds taken into the cell 
and there built up into protoplasm, cell walls, etc. Intracellular 
action, possibly the result of extracellular enzymatic action. 
Carbon : — usually involves dehydration, may also involve re- 
duction (sugars to carbon dioxide). 
No designation of bacterial action involved. 
Nitrogen: — 
1. Assimilation of nitrogen compounds. 
No designation of action. 
2. Assimilation of elementary nitrogen 
(a) by bacterial action. 
(1) By aid of plants. 
Bacterial term — Symbiotic nitrogen fixation 
or Rhizofication. 
(2) By bacteria alone. 
Bacterial term — Non-symbiotic nitrogen 
fixation or azofication. 
(b) By other microscopic plants — yeast, algae, etc. 
No designation of action. 
Sulfur: — Assimilation of compounds only. 
No designation of bacterial action. 
OXIDATION :- — Elements or compounds oxidized partly or com- 
pletely in order to secure growth energy. Action usually in- 
tracellular. 
Carbon: — Action as above. 
No designation of bacterial action. 
