In the last twenty years scientific methods and research have contributed to an ever increasing extent to the improvement of technical processes and to better control of these processes. In the production of crude rubber, for example, the personal skill of experienced experts, which formerly was the only controlling factor, has now been supplemented by a knowledge of how to carry out the process with rigid physico-chemical control. In addition to this, the development of rubber-like materials, such as Buna, has brought to the field of highly elastic materials new accomplishments and methods of investigation of fundamental importance. Since the structural units of rubber and of rubber-like materials lie within the range of colloidal dimensions, the various methods of colloid research have been the chief means of investigation of these materials in the past. Recently the electron microscope has become a new aid to colloid research, and has made possible the direct determination and measurement of the form and size of structural units and their mutual spatial arrangement. In view of this, it was but natural to undertake an electron microscopic investigation of the morphology of rubber and Buna. Even the first broad approach to this problem, which is described in the present communication, makes it evident that the electron microscope technique offers an easy means of gaining an insight into the structure of these systems in various fields of rubber technology.