Growth Measurements 



175 



Controls 

 Fig. 46. A histogram recording the average weekly increment 

 rates of 6 sets of cultures grown in as many different nutrients 

 through 5 successive passages, each of one week's duration. The 

 results are expressed as percentage of the increment rate in the con- 

 trol nutrient containing salts, carbohydrate, and yeast extract. 

 Each vertical column represents the average of 20 cultures for a 

 single week. The solid dots connected by solid lines represent the 

 averages for all five passages (5 weeks) in each solution. (From 

 White, P. R. 1939. Plant Physiol. 14: 531, fig. 4, 182.) 



