Birth of the macromolecule.

The science of chemistry has made considerable advances over the last few hundred years in the characterization of "small" molecules which can be purified and studied by melting, distillation, crystallization and solubility in various liquids. When the study of "large" natural and biological molecules, limited in these properties, rose in significance at the turn of the century, it was first attempted to explain their properties by the concepts of colloid chemistry of aggregation and complex formation. The struggle for the acceptance of the concept of the natural or biological covalently bonded macromolecule, as recalled by Herman Mark, is one of the interesting chapters in recent science history. A specific phase in the establishment of the macromolecular concept centered around the development by The Svedberg of the analytical ultracentrifuge, a versatile tool of highly practical and profound thermodynamic significance.