114 PLANT RESPIRATION 



yet it might be applicable to plant respiration when completed. 

 From a series of experiments on the cells of the blood of birds 

 and on sea urchin eggs on the one hand, as well as on various 

 charcoal powders on the other, Warburg concludes that ''cell 

 respiration is a capillary-chemical process which takes place 

 at the iron-containing surfaces of the fixed cell constituents." 

 That is, it appeared that various amino acids are burned to 

 NH3, COo and HoO when adsorbed to charcoal and that the 

 velocities and accelerations of the oxidation processes are there- 

 by exactly the same as in the case of true cell respiration. The 

 experiments on the eflfect of various narcotics are especially 

 convincing. For equally strong checking of respiration this 

 effect can be expressed by the following equation : 



X • ¥ = K, 



where x represents the number of adsorbed molecules of the 

 narcotic and F is the area occupied by each molecule on 

 the surface of the adsorbent. In this way it appears that the 

 chemical nature of the various narcotics is of no importance 

 and the checking of the oxidation can only be traced to the fact 

 that the substances to be oxidised, e.g. the amino acids, are 

 displaced from the surface by the more strongly adsorbed 

 narcotics and are not oxidised in the solution. The following 

 table of Warburg shows that x • F actually varies but a little 

 for equally strong checking and is therefore almost a constant.^ 



Since oxidation is checked by such small amounts of hydro- 

 cyanic acid, it alone occupies a special position inasmuch as 

 practically no noticeable displacement of the substance to 

 be oxidised could be effected. However, it is evident that 



A constant which is proportional to the magnitude of « • F. 



