COLLOIDAL STRUCTURES I N BIOLOGY* H. FREUSDLICH U n i v e r s i t y College, London, E n g l a n d Receiz,ed Bugust 1 , 1937
It is perhaps not going too far to say that in living organisms a majority of chemical reactions are bound to a special structure, and conversely, though not quite to the same extent, that all structures are bound to chemical reactions. In the development of an egg or in growth, the formation of nen- interfaces and the extension and stretching of old ones always parallel chemical changes. I t is evident that in muscle contraction mechanical processes are closely correlated to chemical one9. When nerves act, one is dealing with the propagation of a chemical reaction in space, because one end of the nerve behaves differently from the other, allowing special substances (acetylcholine, adrenaline) to exude (36). On the other hand A. T7. Hill (28) showed that the nornial structure and irritability of a muscle or st nerve fiber are kept up only if oxidation is going on. Runnstrom (48) proved the same for the nornial structure of eggs. I doubt whether in a living system we are ever dealing with a homogeneous reaction in a one-phase system. Xll processes appear to be either chemical reactions which are propagated in space in specially favored directions, the existing structure changing either reversibly or irreversibly, Le., growing, or they are surface reactions, etc. Thus morphology means much more than mere description, and we are right in being interested in the subtleties of structures in organisms, down to the structural elements of colloidal size. I intend to discuss a few types of structures found in colloidal systems which probably are also important in biological processes. Structures made of rod-shaped particles are frequent. I ani not thinking only of the integuments like those containing cellulose, chitin, etc., which are not “living” in the strict sense of the word. It was one of the most interesting results of x-ray studies-connected with the names of Schemer, R. 0. Herzog, Sponsler and Dore, Mark and I
