2b 



solutions gives 51.36, 29.13, 26. OC and 39.31 atmospheres, 

 from which numbers it "becomes obvious that the osmotic 

 concentration of the sugar solution was much greater than 

 that of the other three. It may therefore be concluded, 

 unless the wall and protoplasm of the spores be readily 

 peinneable to the cane sugar, (which seems highly improb- 

 able), that the inhibiting effects observed with the salt 

 solutions cannot be related primarily to their osmotic 

 properties. 



The relatively high osmotic pressure within the 

 spores here dealt with, as shown by the data just given, 

 renders it unnecessary to consider osmotic pressure as a 

 factor in bringing about the modifications and inhibitions 

 of germination which are now to be considered; the concen- 

 trations of the various salt solutions employed were always 

 far too low to produce any removal of water from the cells. 

 Similarly, the toxicity of calcium, magnesium and potassium 

 nitrates is so very slight as not to require any consider- 

 ation in connection with the combinations of these salts 

 with the heavy metals; in these combinations the salts of 

 the lighter metals have never been used in concentrations 

 higher than C.lm. 



The influence of the nitrates of calcium, magnesium 

 and potassium upon the toxicity of salts of the heavy metals 

 will now receive attention. 



