Prior to the early 1920's, chemists doubted the existence of molecules having molecular weight greater than a few thousand. This limiting view was challenged by Hermann Staudinger, a German chemist with experience in studying natural compounds such as rubber and cellulose. In contrast to the prevailing rationalization of these substances as aggregates of small molecules. Staudinger proposed they were made up of macromolecules composed of 10,000 or more atoms.