Cell structure material | +----------------+----------------+ | | Aliphatic Aromatic (Hemicelluloses, (Lignin, etc., Pentosans, etc.) in presence of | oxygen and under +-------+------------+ aerobic conditions) | | | Fatty acids Furfuraldehyde | | or | | Hydroxymethylfurfuraldehyde | | (in presence of acid) | | · | | · | | · | | · | | · | | · | | · | | · | | · | ↓ ↘ ↓ Calcium carbonate. Humus. The disintegration of the cell and the first stages in the decomposition of the structure material are almost certainly brought about by micro-organisms. Whether they complete the process is not known: purely chemical agencies could easily account for part. The decomposition of protein in the soil has not been studied in any detail. From what is known of the acid hydrolysis and the putrefactive decompositions, however, it is not difficult to draw up a scheme which, at any rate, accords with the facts at present known. It is probable that the protein gives rise to amino-acids, which then break down by one of the known general reactions.