24 STUDIES ON RESPIRATION. IX 



From these data it would seem that effects of CaClo and NaCl on 

 respiration are different from their effects on growth. This difference 

 cannot be an osmotic effect, as the CaCl2 solution, having a stronger 

 osmotic pressure, would in that case be the one that would prevent 

 growth to a greater extent, but this is not the fact. 



SUMMARY. 



1. In the presence of 0.05 per cent dextrose the respiration of 

 Aspergillus niger is increased by NaCl in concentrations of 0.25 to 

 0.5m, and by 0.5m CaCl2. 



2. Stronger concentrations, as 2m NaCl and 1.25m CaClo, decrease 

 the respiration. The decrease in the higher concentrations is 

 probably an osmotic effect of these salts. 



3. A mixture of 19 cc. of NaCl and 1 cc. of CaClo (both 0.5m) showed 

 antagonism, in that the respiration was normal, although each salt 

 alone caused an increase. 



4. Spores of Aspergillus niger did not germinate on 0.5m NaCl (plus 

 0.05 per cent dextrose) while they did on 0.5m CaCl.> (plus 0.05 per 

 cent dextrose) and on various mixtures of the two. This shows that 

 a substance may have different effects on respiration from those which 

 it has upon growth. 



