462 



STATE BOARD OF AGRICULTURE. 



average total aininonia formed, amounts to ±75% after two days, 40% 

 after four days, 22% after six days, 24% after 10 days and 7% after 20 

 days. This means, in non-mathematical terms, that the older the cultures 

 the better comparable are the data. 



Among the sand cultures there is one series lower than all others, 

 namely Series V. An explanation for it cannot be given. I^one of the 

 series shows permanently higher data than the others. The greatest 

 deviation of corresponding cultures of dillereut series is shown in the 



following table. 



TABLE III. 

 Maximum Deviation of Quartz Sand Cultures of Different Series. 



The maximum deviation between corresponding cultures seems to in- 

 crease slightly with age, but not nearly as fast as the total ammonia, so 

 that the relative error becomes smaller with the age of culture. 



Comparison of Solutions, Soil and Sand Cultures. — The true picture 

 of the average development of B. viycoidcs in sand cultures and in solu- 

 tion is represented in the averages shown in Table IV. The optimum 

 moisture for />'. mycoidcs in this quartz sand is about 20%. The series 

 with 5% moisture is bettei omitted from consideration, being based on 

 only one set of duplicates with, rather questionable data. The series 

 with 10% moisture has the same endpoint as the peptone solution, but 

 ferments much faster in Ihe beginning. The cultures with 15% are su- 

 perior in every j/oint, and the cultures with 20% are higher again than 

 those with 15%. A further increase of moisture lowers the amount of 

 ammonia formed. The peptone solution might be considered as the ex- 

 treme of the increase of moisture, the sand disappearing completely. 



TABLE IV. 

 Ammonia formed in Quartz Sand and in Peptone Solution. (Averages from Table II.) 



5 % moisture (1 duplicate) 



10% moisture (4 duplicates) . . . 

 15% moisture (4 duplicates) . . 

 20% moisture (5 duplicates) . . , 

 25% moisture (3 duplicates) . . 

 Peptone solution (6 duplicates) 



2 days. 



1.2 

 2.6 

 3.0 

 3.3 

 2.0 

 0.9 



4 days. 



1.7 

 4.0 

 4.7 

 4.7 

 4.0 

 2.0 



6 days. 



3.8 

 4.6 

 5.4 

 6.0 

 5.2 

 3.2 



10 days. ' 20 days. 



3.2 

 5.7 

 7.0 

 7.6 

 7.2 

 5.0 



1.3 

 G.5 

 7.7 

 9.4 

 9.1 

 6.5 



The four soils of the first two series show the moisture optimum at 

 25%. They differ from the sand in their very weak development at 

 10%, while they are superior to sand at 20 to 30%. The surface soil of 

 Series I is a much better medium for B. inycoidcs than the subsoil, 

 .showing nearly twice as high an endpoint. In the earlier stages of the 

 bacterial growth this difference is much larger and it seems as if the 



