p. G. GUSTAFSON 



23 



plastic material is used in oxidation. If this is true it is easily con- 

 ceivable that the oxidation of such material might not be affected in 

 the same way by CaCl2 as the oxidation of dextrose. 



Experiments on antagonism between NaCl and CaCl2 were also 

 made. A solution containing 19 cc. of NaCl and Ice. of CaCls (both 

 0.5m) gave the best results. In this mixture the rate of respiration 

 was practically normal (Fig. 3, Curve C). Other proportions gave 

 more or less increase. 



Fig. 3. Respiration of Aspergillus niger. The broken straight line to the left of 

 the point marked on the abscissa represents the normal rate of respiration in 

 0.1 per cent dextrose before the addition of the salt. Curve A represents the res- 

 piration in 0.5m NaCl, Curve B in 0.5m CaCb, and Curve C in a mixture of 19 cc. 

 of NaCl and 1 cc. of CaCla (both 0.5m). The control (dotted line) and C are prac- 

 tically identical. All these experiments were made in 0.05 per cent dextrose. 

 Curve A is an average of 3, Curves B and C of 4 experiments. The probable 

 error was less than 3 per cent of the mean. 



In order to compare these results with the effects on growth spores 

 were sown on solutions of NaCl and CaCl2 (with 0.05 per cent dex- 

 trose), on various mixtures of these," and on 0.05 per cent dextrose 

 alone. For these experiments Petri dishes were used. The extent of 

 germination was determined by microscopic examination. 



The following results were noted : In NaCl there was no germination; 

 in 49 cc. of NaCl-f-1 cc. of CaCl2 some germination; 24 cc. of NaCl-f- 

 1 cc. of CaCl2, and 9 cc. of NaCl + 1 cc. of CaCl2 showed a growth 

 which increased in proportion to the amount of CaCl2; 4 cc. of NaCI 

 -f 1 cc. of CaCl2 seemed to produce the best growth; 1 cc. of NaCl + 1 

 cc. of CaCl2 and CaCl2 alone showed fairly good growth; 0.05 per cent 

 dextrose produced rather poor growth. 



" Both NaCl and CaCb were 0.5m and were dissolved in 0.05 per cent dextrose^ 



