100 



SCIENCE 



[N. S. Vol. XXXIV. No. 865 



ble.'^ Visibility depends upon size, differ- 

 ences in refraction, adsorption of stains or 

 reagents and similar more or less accidental 

 phenomena. Plainly there may be physic- 

 al and chemical structure which does not 

 happen to be visible. It is to such structure 

 dependent upon the heterogeneous nature 

 of protoplasm and to the consequences aris- 

 ing from its nature that I wish to draw 

 your attention to-day. 



Protoplasm must have some such organi- 

 zation, other than a merely chemical one. 

 Otherwise we- can not understand how so 

 many intricate reactions can take place in 

 an orderly fashion within the narrow con- 

 fines of a single microscopic cell. Let me 

 illustrate by an example. The yeast cell 

 converts sugar into alcohol, carbonic acid 

 and water. Under certain conditions it 

 also converts sugar into glycogen which it 

 may store for a long time within itself, or 

 which it may soon reconvert into sugar and 

 then into alcohol. Under certain condi- 

 tions it may oxidize alcohol. It synthesizes 

 protein and cellulose. It forms glycerine, 

 succinic acid and amyl alcohol. It may re- 

 duce sulphur to sulphuretted hydrogen. It 

 performs undoubtedly a whole series of 

 cleavages, syntheses, oxidations and reduc- 

 tions, and yet, examined under the micro- 

 scope, it appears fairly homogeneous. No 

 structure is visible capable of explaining 

 how in this small space so many processes 

 can go on side by side in an orderly fashion 

 without interfering with one another. In a 

 single test-tube it is manifestly impossible. 

 In any homogeneous medium it is mani- 

 festly impossible. However, in a heteroge- 

 neous medium, such as an emulsion, it is 

 conceivable. We have merely to imagine 

 the reactions as taking place in different 

 phases and to remember that at the points 

 of contact of two phases membranes 



" Ostwald, Wo., ' ' Grundriss der Kolloidcheinie, ' ' 

 S. 32, Dresden, 1909. 



form. By the term "membrane" we 

 must understand in this connection merely 

 the condensation of material at a surface 

 serving to separate two phases. We have 

 then imagined a structure for protoplasm, 

 part chemical, part physical, sometimes 

 visible, sometimes invisible, in which many 

 reactions might go on side by side as thor- 

 oughly separated as though in separate 

 test-tubes. They would, however, go on 

 more effectively than in separate test-tubes, 

 because in these no influence of one reac- 

 tion upon the other is possible, whereas in a 

 heterogeneous system such an influence 

 between two separated reactions is conceiv- 

 able. A reaction taking place in one phase, 

 may, either by yielding products soluble in 

 another phase, or by changing concentra- 

 tions, affect one or two or every other phase. 

 Interrelations of this kind might very well 

 lead to what is ordinarily termed coordina- 

 tion. 



Indeed, there is some evidence that some 

 of the coordination is of this type. When 

 a piece of protoplasm dies, not all the func- 

 tions which up to that time it has exercised, 

 cease at once. Some of them may continue 

 for a long time, and these are usually due 

 to enzyme action. In the dying mass res- 

 piration may continue as well as many 

 other functions, but while they may be 

 qualitatively the same, quantitatively they 

 differ. The balance present during life is 

 destroyed and certain reactions gain the 

 upper hand, eventually dominating the 

 field till everything else is suppressed. 

 Coordination, the great characteristic of 

 life, disappears. Anything which inter- 

 mixes protoplasm, hence disturbs the 

 phases, destroys coordination. Freezing is 

 one of the agents exerting this effect upon 

 many forms of protoplasm, for by causing 

 some of the water to crystallize, it most 

 effectively disturbs the balance of the 

 phases. We note this, for instance, in the 



