July 28, 1911] 



SCIENCE 



99 



to be regarded as a very complex though 

 rather homogeneous mixture of materials, 

 some of which were assumed to be alive. 

 The latter were supposed to be huge, com- 

 plex molecules, protein in the main, but 

 not necessarily entirely so. The vital quali- 

 ties inherent in protoplasm were supposed 

 to run parallel with the complexity and 

 instability of these huge living molecules. 

 Essentially this was a chemical conception 

 of protoplasm different from ordinary 

 chemical conceptions only in that these 

 hypothetical, hopelessly complex mole- 

 cules were assumed in some way to 

 possess the power of regenerating them- 

 selves when in consequence of their insta- 

 bility they fell to pieces. As we look back 

 now, we can see that apparently the only 

 reason why proteins were chosen to fill this 

 role was that at that time far less was 

 known about proteins than about the other 

 constituents of cells. By some it was even 

 imagined that if only it were possible for 

 organic chemists to know the structure of 

 such molecules completely, a deep insight 

 would be gained into the causes of life. 

 Others, less sanguine, believed that this 

 could never be, because in the process of 

 analysis the molecule ceased to live, was 

 changed, depolymerized, so that what was 

 studied had in the very process of study 

 lost its vital properties. Even as recently 

 as the beginning of Emil Fischer's work 

 upon protein the hope was expressed that 

 since he had brought the synthesis of pro- 

 tein within striking distance, a more inti- 

 mate knowledge of the nature of life would 

 follow. And yet, though it is now possible 

 to make substances very similar to some 

 proteins with very high molecular weights, 

 and though we may rest assured that all 

 the complex substances occurring in living 

 things will eventually be so well known 

 that they will be ranged without wonder 

 and without comment with the vast horde 



of organic compounds, nevertheless, by such 

 achievements alone, only a limited insight 

 into the mechanisms of life can be gained. 

 The reason is that a study merely of chemi- 

 cal constitution, however necessary, will 

 carry us but a very little way in under- 

 standing even the simplest processes which 

 take place in protoplasm, unless it be com- 

 bined with a study of structure, and of the 

 dynamics resulting from both. 



Now when I speak of structure I do not 

 mean necessarily anatomical structure that 

 is visible with the microscope. Still a study 

 of even microscopic structure has been and 

 is of incalculable value. With such studies, 

 the name of Biitschli is indissolubly con- 

 nected. He it was who first emphasized the 

 fact that protoplasm has the structure of a 

 foam or a network with interstices filled 

 with material of a physical nature differ- 

 ent from the network, or finally, the struc- 

 ture of an emulsion. Indeed, his anatomic- 

 al observations led him to study foams, 

 and emulsions, experimentally, in the hope 

 of being able to interpret his anatomical 

 studies more rationally. His experiments 

 became of fundamental importance in 

 stimulating work in certain fields of pure 

 colloidal chemistry and of the dynamics of 

 surfaces. He understood better than any 

 one before his time the anatomical structure 

 of protoplasm. He was the first to point 

 out that protoplasm is heterogeneous, con- 

 sisting of at least two phases touching each 

 other by minimal or capillary surfaces.^ 

 We shall learn to appreciate the great sig- 

 nificance of this idea. Even Biitschli, how- 

 ever, found that many heterogeneous sys- 

 tems appeared homogeneous under the 

 highest powers of the microscope, because 

 the differences in refraction between the 

 phases was insufficient to render them visi- 



' O. Biitschli, ' ' tJntersuehungen ueber mikro- 

 skopische Schiiunie und das Protoplasma, ' ' Leip- 

 zig, 1892. 



