Page:Popular Science Monthly Volume 66.djvu/155

Rh of the molecule that would serve to illuminate our field of vision and give us a clear conception of the chemical constitution of this group of physiologically important ground substances in living protoplasm.

As is well known, the proteid bodies constitute a group of widely divergent substances. Of these, the basic protamines are undoubtedly the simplest and lowest in the scale, and it is quite probable, as suggested by Kossel, that these substances constitute the nuclei of all proteids. The protamines differ somewhat among themselves, but as a group they are characterized by their high content of diamino-acids, especially arginin. Thus, salmin yields on decomposition 84 per cent, of arginin, clupein 82 per cent., cyclopterin 62 per cent., and sturin 58 per cent. Sturin also contains 13 per cent, of histidin and 12 per cent, of lysin, while the other protamines appear to contain no diaminoacids aside from arginin. Further, the protamines contain cliamidovalerianic acid, monoamido-valerianic acid, tyrosin or p-oxyphenylamidopropionic acid, skatolaminoacetic acid, a-pyrrolidincarbonic acid and serin. Salmin has also been shown to contain alanin, leucin, probably also phenylalanin and aspartic acid.

If we pass from the simplest of the proteid bodies to the most complex, as the nucleins, we find present in the latter not only arginin, lysin and histidin, but, in addition, such bodies as thymin, the purin bases, leucin, aspartic and glutamic acids, two sulphur-containing groups, furfurol-forming groups, pyrrolidincarbonic acid, a skatolforming group, phosphoric acid, amidovalerianic acid, a levulinic acidforming group, glycosamine, pentose, uracil and probably phenylamidopropionic acid. In the histon from the nucleohiston of the thymus, we find in addition to the hexone bases and the monoamido-acids characteristic of the ordinary albuminous bodies such substances as glycocoll, cystin and alanin.

These statements, brief and incomplete though they are, will serve to illustrate the complexity of the proteid molecule, and at the same time they indicate the close genetic relationship which unquestionably exists between the varied members of this large group of substances. There is no doubt that Kossel and his co-workers in their efforts to unravel the constitution of the protamines are pursuing a wise course in paving the way for a comprehension of the exact nature of the more complicated proteids. There is no doubt that the protamines of one