56 TRANSACTIONS AND PliOGKEDINGS OF THE [Sess. Lxv. 



spite of respiration, however, the processes of assimilation 

 and reproduction continue to go on in the Vjioniolecule, and 

 the number of atoms of oxygen and carbon are regularly 

 doubled. Further, if it were a mere oxidation of carljon 

 atoms, the amount of carbon dioxide given off would equal 

 that of the oxygen absorbed ; and the two phenomena — 

 absorption of oxygen and emission of carbon dioxide — 

 would be simultaneously accomplished, the first ceasing, 

 the second would likewise come to an end. To give the 

 prevalent opinion of botanists on this point, we cite from 

 Vine's "Physiology of Plants," p. 196 : "There is no such 

 constant relation between the volumes of carbon dioxide 

 exhaled and the oxygen absorbed in respiration, and the 

 processes of destructive metabolism are so complex, that we 

 cannot account for the relation, whatever it may be, 

 between the volumes of these gases in any particular 

 case." 



Respiration is an oxidation of the biomolecule — the 

 oxygen is fixed chemically in the biomolecule, and remains 

 there some time. The oxidation of the molecule of 

 methyl-ethyl-ketone is a case in point — the oxygen is 

 fixed in the molecule, and the latter as a result undergoes 

 chemical transformation, whereby it splits into two mole- 

 cules of acetic acid, without any evolution of carbon dioxide. 

 Disengagement of carbon dioxide is thus not an inevitable 

 result of oxidation ; and, further, it may result from other 

 chemical reactions without any oxidation at all, e.g. acetic 

 acid reacting on isocyanate of ethyl gives ethyl-acetamide 

 and carbon dioxide. It may be pointed out that botanists 

 generally admit that the evolution of COg is not directly 

 connected with the absorption of 0. Van Tieghem held 

 this view as far back as 188-4. He was led to the same 

 view as the result of experiment as our author has arrived 

 at by theoretical considerations. We might cite here, also, 

 the experiments of De Saussure, Mayer, and Deherain, 

 which are all in favour of the view that the oxygen is 

 combined with the biomolecule. Succulent leaves of Agave, 

 Saxifrages, Crassulacea, stems of Cactus, and fruits were 

 found by these investigators to be able to absorb oxygen with- 

 out giving off any carbon dioxide in return. " De Saussure 

 found that he could not extract by means of the air-pump 



