As far back as 1905, Kossel has had indicated the existence for the important alkaline aminoacids, arginine and histidine, of the C N-C N group, found also in the nitrogen containing bases of nucleic acid. The hypothesis which we advance that this C N-C N group would represent the starting point of the biological realm itself, can surely be subject to discussion.

Progressively more evidence is being obtained that important organic compounds can appear from the constituents of the atmosphere itself, under the influence of electrical discharges or of ionizing irradiation. While Hen riet (268) was the first to show that formic acid is present in rainwater, it was Loew (269) who obtained glycine from the constituents of the atmosphere submitted to electrical discharges. By utilizing, under the same condition, mixtures similar to those considered to have been present at the time when life is supposed to have started, Miller obtained, through electrical discharges, many amino acids and other substances especially glycine and formic acid (270, 271). Miller's results were extensively confirmed (272 to 279).

The irradiation of the mixtures of gases considered present in the atmosphere millions of years ago has led to the synthesis of many other substances such as formic, acetic, propionic, succinic and even tricarboxilic acids (280, 287). From these, we consider of especial importance the members with a second nitrogen group far in the molecule, as diamino succinic acid, iminodiacetic or iminoacetic propionic acid.

The synthesis of the strongly positive C N-C N group which we consider as the starting point of the biological realm, seems thus to have taken place rather under the influence of radiation. This fact appears especially important since it would relate more directly the beginning of the biological realm to the intervention of the radioactive elements, which according to our systematization of the elements, form the period which corresponds to the lowest levels of the hierarchic organization. (See Chapters 2 and 5)

The NH2 and C N C N groups appear as entities taking part in the formation of alkaline amino acids

Fig. 201. The NH2 and C N-C N groups appear as entities taking part in the formation of alkaline amino acids as well as of nitrogenous bases. The bond to a chain having an amino acid group in the first case, results in a new entity—an alkaline amino acid—which polymerizes through the amino acid group. Through the alkaline group it conserves its positive electrical character. In the nitrogenous bases, the C N-C N group is part of the cycle. Bound to phosphoric acid, the results are acid entities with negative charges.

The further evolution of the C N-C N formation seems to have taken place in two directions—one in which one or two such groups have formed a cycle and given rise to the nitrogenous bases, purines and pyrimidines, and the other in which this energetic group has bound an aliphatic amino acid chain, this last probably originated under the influence of electrical discharges. The two principal alkaline amino acids, arginine and histidine, have thus appeared. (Fig. 201) The double capacity of the alkaline amino acids, to bond other amino acids through their amino acid groups and thus to form polymers, and to bond acid substances through their alkaline polar groups and make new hierarchic entities, has given these substances their peculiar organizational role. C N-C N, alkaline amino acids and histones (or in fish, the protamins) would thus represent the first hierarchic steps in the progression of the biological series.

A few words should be said about lysine, the alkaline amino acid with an amino group as alkaline terminal group. Although together with the other alkaline amino acids, it enters in the formation of histones, it seems to have another important biological role, that of an agent intervening in the metabolism of lipids.