NUMBERS OF MICROORGANISMS 



25 



TABLE 2 

 Numbers of microorganisms in the soil, as shown by the plate method* 



BACTERIA AND ACTINOMYCES 



64 



96 

 81 

 53 

 96 

 69 

 72 

 62 

 69 

 77 



106 

 93 



98 

 87 

 91 



Colonies 



106 

 101 

 89 

 84 

 116 

 76 

 82 

 93 

 76 

 84 



52 

 78 

 61 

 93 

 106 



Total = 4173 



Mean = 83.46 ± 1.5 

 a = 15.69 ± 1.07 

 C.V.= 18. 8 ±1.27 per 



cent 

 A3 = ±2.22 

 Em = 1.8 per cent 



ACTINOMYCES 



Colonies 



11 



10 

 9 



17 

 9 



15 

 7 



11 



13 

 10 



11 



15 



13 

 12 



7 



11 

 9 

 9 



12 

 6 



7 

 13 

 14 

 12 

 10 

 12 

 13 

 15 

 12 

 11 



14 

 16 

 13 

 12 

 14 

 12 

 11 



9 

 15 



9 



4 

 17 

 11 

 13 

 21 



Total = 565 



Mean = 11.3 ± 0.30 

 ff = 3.16 ± 0.20 

 C.V.= 27.96 ±1 89 per 



cent 

 Az = ±0.45 

 Em = 2.7 per cent 



Colonies 



'3 



6 

 3 

 5 

 2 

 3 

 4 

 2 

 3 

 2 



4 

 3 

 3 

 5 

 1 

 1 

 1 

 1 

 

 1 



2 

 1 

 1 

 1 



2 



Total = 138 



Mean = 2.76 ±0.16 

 a- = 1.73 ±0.11 

 C.V.= 62.67 ±4.23 per 



cent 

 Az = ±0.245 

 Em — 5.8 per cent 



* In each group of 10 figures the number of colonies on each of 10 plates for each 

 soil sample is shown. 



Approximately two-thirds of the determinations are expected to lie on 

 both sides of the mean, within that deviation. 



