EXPERIMENT STATION BULLETINS. 



485 



TABLE XVIII. 

 Alcoholic Fermenlalion of a Sugar Solution with Glass Beads. 



Solution. 



10 cc 

 10 cc. 

 10 cc 

 10 cc 

 10 cc 



10 cc 

 10 cc 

 10 cc 

 10 cc 



Glass 

 beads. 





 33.0 

 49.5 

 62.0 

 99.0 



165.0 

 247.0 

 495.0 

 990.0 



Moisture in per^cent. 



of 

 weight. 



of pore 

 space. 



Sugar fermented. 



5% 

 yeast. 



50-53 

 56.6 

 65.6 

 56.2 

 37.5 



37.5 

 30.5 



0. 



0. 



11.4% 

 yeast. 



17% 

 yeast. 



Contact surface 

 solid to liquid. 



circ 8 sq. cm. 

 1 ,300 sq. cm. 

 2,000 sq. cm. 

 2,500 sq. cm. 

 4,000 sq. cm. 



6,600 sq. cm. 



9,900 sq. cm. 

 19,800 sq. cm. 

 39,600 sq. cm. 



The inoculum in this experiment is so large that multiplication can 

 be neglected. The active mass in the three different series was approxi- 

 mately 1:2:3. The maximum fermentation was found to take place 

 in the water-saturated "soil," at 100 to 150% of the pore space. That 

 the water-saturated soils are a better medium for anaerobic organisms 

 than liquids without sand, has been discussed in the previous chapter 

 (p. 34). 



The grainsize being constant, the fermentation is entirely regulated 

 by the moisture content. Decrease of moisture will decrease the film 

 diameter and increase the aeration, both unfavorable for the anaerobic 

 fermentation by yeast. The result must be a continuous decrease of 

 fermentation with decreasing moisture. The data prove this to be the 

 case in every instance. 



The influence of the inoculum is surprisingly large. The time be- 

 ing limited to 12 hours, the data can by no means be regarded as end- 

 points. Otherwise, the data in all water-saturated soils should be the 

 same in all three series. But that, at 2% moisture, an increase of 

 inoculum from 5% to 17% causes an increase of decomposition from 

 to 63% seems rather incredible. Since nothing is said concerning 

 the method of inoculation or analysis, it is impossible to find whether 

 and where there was a chance for a mistake. The moisture film at 1% 

 moisture is 2.5 yu,, i. e. smaller than the diameter of the yeast cell. 



Bacterium lactis acidi in Sand a/fid Solution. — Original experiments 

 concerning the development of anaerobes in soil were carried on only 

 with Bacterium lactis acidi. Though this bacterium is not strictly anae- 

 robic, it is decidedly favored by anaerobic conditions, and the fact that it 

 is able to grow under aerobic conditions to some extent is more an ad- 

 vantage than disadvantage in these experiments. Especially the methods 

 of handling and counting these organisms are greatly simplified since 

 no precautions have to be taken to avoid contact with oxygen. 



The first experiment was carried on with Strain II* of this laboratory. 

 Four different series were made, A, milk in deep layer, B, milk in shal- 

 low layer (about 4 times as large a surface), C, 50 cc. milk in 100 g. 

 of medium quartz sand (the milk stood a few millimeters over the sand) 

 and D, 20 cc. milk in 200 g. sand which mixture allowed a good aera- 



♦Conceming the properties of the two strains, see Mich. Agric. Ooll. Expt. Sta. Technical Bui. 10 



