THE INFLUENCE OF CHEMICAL FACTORS 67 



i. The lipoid-soluble substances may act in two different ways ac- 

 cording to their chemical structure. In some of them the effect de- 

 pends upon the presence in the molecule of certain chemically active 

 radicles and these are called by Warburg specific (#), in others chemi- 

 cally active radicles are absent, they are non-specific (//). This latter 

 group comprises the ordinary narcotics. 



I. (a) Among the specific lipoid-soluble substances Warburg 

 has investigated aldehydes, which inhibit oxidations, ammonia and 

 amines which stimulate oxidations in very small doses, while they 

 inhibit in greater concentrations, and prussic acid which is the most 



powerful inhibiting substance known, a concentration of KCN 



i ooooo 



being sufficient to diminish the oxygen consumption of sea urchin eggs 

 about 30 per cent. 



1. (/>) The non-specific narcotics have invariably an inhibiting ef- 

 fect upon oxidations, and for each series of homologous substances the 

 effect increases with the number of carbon atoms in the molecule as 

 shown by the following concentrations of urethanes which have been 

 observed to diminish the oxidations in different cells by 30 to 70 

 per cent. : 



Concentration in 



Red Corpuscles Central Nervous 

 of Birds. System of Frogs. 



Methyl-urethane 1*3 Mol. 1-3 Mol. 



Ethyl- 0-33 0-45 



Propyl- 0-13 0-13 



Butyl- ,, (iso) . . . . . 0-043 0-06 



Phenyl- ,, ...... 0*003 > 0*006 ,, 



The effects of each substance on very different cells are nearly the 

 same and the effects on a non-vital enzyme reaction, the alcohol fer- 

 mentation in yeast juice, are also of about the same magnitude. 



2. The lipoid-insoluble substances. 



Chloride of sodium. A solution of pure NaCl, isotonic with sea- 

 water, increases enormously (five times) the respiratory exchange of fer- 

 tilized eggs of the sea urchin Strongylocentrotus. This effect can be 

 abolished by a trace of NaCN ,or by CaCl 2 . The pure NaCl solution 

 destroys the eggs very rapidly and in this phase the oxidative energy 

 falls off rapidly. On the respiration of a number of other cells (red 

 corpuscles, muscles) NaCl has no effect whatever. 



Ions of heavy metals. The ions of gold, silver, and copper, in 

 concentrations about io~ 5 normal, increase the oxidations in fertilized 



5* 



