Vitality and Organization of Protoplasm. 41 



simply mediated by a machine-like construction of the same, but that 

 chemical changes in the constitution of the muscular substance itself 

 causes its contraction. "From these observations, I think, I may con- 

 clude, that in the muscular fibre its contraction is not mediated by any 

 kind of machinery, but that changes in the chemical constitution of 

 the muscular substance itself are the cause of the entire process of con- 

 traction." In 1881, in an article in Pfluger's Archiv. Zur Lehre von \ 

 der Muskelkontraction," after two entire years of further observation, 

 1 ventured to advance a new interpretation of muscular contraction, in 

 which I laid stress on the positive, reintegrative, expansive phase of 

 muscular activity, as compensation of the negative, disintegrative,, con- 

 tractive phase, which latter remains still the only one physiologically 

 acknowledged. These observations made nutrition or the functional use 

 of food, and oxydation or reduction of organic substances, appear in an 

 entirely different light. The office of nutrition was recognized as having 

 essentially to supply and prepare assimilative material fit to reintegrate 

 the functionally deteriorated substance. And the office of oxydation 

 evinced itself as having essentially to reduce the eliminable products or 

 waste substances of functional disintegration. 



The assimilation of nutritive material consists in the power of the 

 living sul)stance to fill the chemical gap caused by functional disintegra- 

 tion. This direct conclusion from observable facts scientifically explains 

 in what nutrition really consists, and shows how assimilation is ren- 

 dered possible. The force which compels assimilation by causing life- 

 less matter to be incorporated in the living substance, and to become 

 itself thereby vitalized ; this vitalizing force consists in the avidity of 

 functionally deteriorated protoplasm to restitute its chemical integrity. 



The current hypotheses of individuated molecular units have turned 

 vital assimilation into an inscrutable mystery. Under their sway it 

 remains utterly unintelligible how lifeless outside matter can possibly 

 be converted into swarms of vitalized and vitalizing molecules, of which 

 organisms are then supposed to be built up. The untenability of such 

 aggregational theories have been here sufficiently exposed. It has been 

 found that without a correct understanding of assimilation, and there- 

 with of organic growth, neither self-division, nor other modes of repro- 

 duction can be scientifically explained. For assimilation and growth are 

 processes upon which organic reproduction in all its fonns is altogether 

 dependent. We have now positively recognized that assimilation, or the 

 vital and organic incorporation of nutritive material consists nowise in 

 a mysterious new formation of vital units, either by spontaneous gen- 

 eration, or by the self-division of already existing units: but that it is 

 simply a result of chemical reintegration of the living substance by 

 means of combination with complemental material. Of course, in a 

 general way it is taken for granted that organs repair the waste they 

 suffer during functional activity. Kut by what means such organic 

 restitution is effected has hitherto remained in the dark. 



It is instructive to elucidate the process of assimilation by tracing it 



