The complete polymerization of phenols and proteins (one of the processes involved in the forma tion of humic substances) was explained. It was shown that fly (Bibio marci) larvae and earthworms (Aporrec todea caliginosa) participate in the complete polymerization of phenols and proteins. In a laboratory experi ment, invertebrates participated in the degradation of organic matter and the synthesis of humic substances, which was proved in experiments with 14Clabeled phenols and proteins. The same organic substances (phenols and proteins) without the impact of invertebrates were used as the control substances. The distributions of the 14C isotope in alkaline extracts separated by solubility in acids (humic and fulvic acids) was compared to those of the control substances. The portion of the 14C isotope in the humic acids in the excrements of Bibio marci was higher than that in the control substances. The content of 14Clabeled humic substances in the excrements of the earthworm Aporrectodea caliginosa exceeded t