Sentence:  His experiments show “that about four-fifths of our disassimilations are the result of transformations within the body, comparable to the oxidation of alcohol, and that the remaining one-fifth of the <WSD>disassimilations</WSD> are formed at the expense of the living tissues themselves, free of all demands on foreign oxygen." 
Meaning of the word marked with <WSD> tags:  (catabolism) (metabolism with the release of energy)