468 



STATE BOARD OF AGRICULTURE. 



Series VI. 



Soil. 



Coarse sand . 



Medium sand . 



Pine sand . 



Moisture. 



20% 

 25% 

 30% 



Peptone solution . 



2 days. 



107.0 

 81.0 

 49.0 



4 days. 6 days. 



128.5 

 94.5 

 54.3 



199.0 



150.5 



85.5 



11 days. 



214.0 

 164.0 

 104.5 



21 days. 



251.0 

 176.0 

 109.0 



42.7 

 59.7 

 40.7 

 24.4 



116.0 



102.0 



66.6 



42.8 



15.4 

 15.0 

 29.5 

 11.1 



4.8 



23.2 

 21.8 

 52.0 

 23.0 



168.0 



123.5 



88.3 



55.0 



69.5 

 54.3 

 65.2 

 34.8 



8.8 



12.6 



217.0 



158.0 



115.7 



92.8 



73.3 



65.8 

 69.2 

 38.0 



14.6 



238.0 



172.0 



121.0 



97.0 



83.0 

 65.2 

 79.4 

 46.7 



25.5 



2VeM> Comparison of Sand, Soil and Solution. — These data are not 

 absolutely comparable (nor were the previous ones,) on account of the 

 peptone being added in proportion to the weight of sand or soil. Con- 

 sequently, the sand with 5% moisture and 1% peptone actually con- 

 tains a solution of 20% peptone which is compared with a 1% pep- 

 tone solution in the liquid culture. As. far as the peptone itself is 

 concerned, this does not make a serious difference, because a bacterium 

 that decomposes only one-fifth of its food in a 1% solution of peptone 

 will not be able to destroy more in a 20% solution.* But consider- 

 ing the fact that in the sand cultures, the mineral matter is very scarce, 

 coming entirely from the commercial peptone, it is evident that a more 

 concentrated peptone solution is better suited for growth on account 

 of providing more material for cell construction. However, three of 

 these series have been checked with parallel cultures which contained 

 mineral fertilizers, and in those, the increase ol' ammonia due to miner- 

 als averaged not more than 40% while the differences we are dealing 

 with in this experiment amount to several hundred pKjr cent. Later 

 experiments will show that the differences are similar even when the 

 peptone concentration is constant. They demonstrate further that the 

 supposition of some easily decomposed nitrogenous compounds in the 

 peptone cannot be accepted as an explanation. 



TABLE VII. 



Influence of Quartz Sand upon Ike Ammonification by B. mycoides. Averages of Sand Cultures from 



Table VI. 



Moisture content 

 of sand. 



Series of 

 experiments. 



I. II. V, VI 



I, IT. V. VI 



I, II, III, IV. VI. 



25% II. V. VI. 



(100%) solution. . . I. II, III. IV, V. VI. 



Peptone 

 concen- 

 tration. 



days. 



4 

 days. 



72.5 

 79.5 

 57.8 

 44.8 

 20.4 

 2.7 



110.0 



102 2 



90^5 



63.8 



40.7 



6.8 



6 

 days . 



245.0 



140.5 



104.0 



81.6 



53.0 



10.9 



10 

 days. 



206.0 

 174.5 

 134.8 

 103.3 

 73.3 

 16.7 



20 

 days. 



SI .0 



20.5 . 



148. 3 



127.9 



92 . 8 



22.2 



♦Later experiments, soon to be published have shown that concentration of peptone plays a more 

 important part than was assumed in drawing these conclusions. 



