290 PKOCEEDINGS OF THE INDIANA ACADEMY OF SCIENCE. 



aliquots of each of these bacterial dilutions and 90 cc of distilled water, 

 l-^^QCO bacterial dilutions were made, and, following the same procedure, 

 1-40.000 bacterial dilutions were made. 



When ammonium hydroxide is added to acid soil containing a large 

 amount of organic matter the solution becomes dark colored in proportion 

 as the soil is acid. One cc portions of strong ammonium hydroxide were 

 added to each of the bacterial dilutions made and it was found that the 

 color produced was darker in each ease where the 10 cc aliquots had been 

 taken from the original 1-4 bacterial dilutions first made up. The fact that 

 the amounts of material soluble and insoluble in water which would react 

 with ammonium hydroxide were different in high dilutions made when 10 

 cc aliquots were taken at the start from what they were when 1 cc aliquots 



Pl.ATK VI. 



were taken at the start, is conclusive evidence that the results of working 

 the two ways are not the same. Figure V shows the results using soil No. 1. 

 The t rto l)ottles at the left are the 1-400 bacterial dilutions while those at the 

 right are the 1-4,000 liacterial dilutions. The left hand bottle in each case 

 shows the result of using 10 cc aliquots from the start. When tested in a 

 colorimeter the depth of color of the solution in the left hand bottle of each 

 set was about 1.5 times that in the corresponding bottle where a 1 cc aliquot 

 was taken at the start. 



Figure VI shows the results using soil Xo. 2 which was much more acid 

 and which containe<l over seven times us much organic matter. Six of the 

 bacterial dilutions made were photographed, the two at the left being the 

 1-400. the middle two the 1-4.000. iiul the two at the right the 1-40,000 

 bacterial dilutions. The left liand bottle of each set is the one where 10 cc 



