BY R. GREIG-SMITtf. 



739 



excepting the two-fifth. The effect of dilution is peculiar, but, 

 beyond recording the counts, little can be said, at present, regard- 

 ing the matter. 



A spell of dry weather prevented the continuation of similar 

 tests at the time, and, therefore, a quantity of soil was put into a 

 Biichner porcelain-funnel, and treated, during one day, with a 

 quantity of distilled water, equivalent to one inch of rain. On the 

 following day, the drainage was filtered and tested, the soil mixed 

 and divided into portions, each containing 200 grams of dry soil. 

 These were stored in bottles at 22°, and tested from time to time. 

 Experiment iv. 



A rich, brown, alluvial soil, from the Hawkesbury Agricultural 

 College, had been stored in the laboratory for about a year. It 

 contained 1*5% of moisture. Two hundred gram.portions were 

 weighed out into 700 c.c. bottles, and moistened with 40 c.c. of a 

 soil-suspension of the same soil, which "had been growing maize- 

 plants in the glasshouse. Ten grams of the soil were shaken with 

 500 c.c. of sterile water, to make the suspension. The bottles were 

 corked, and divided into two sets, one being kept at 28°, the other 

 at laboratory-temperature (15° to 20°). When required, each bottle 

 received 160 c.c. of water containing 4 c.c of 10% potassium 

 sulphate. The shaking and nitration -were done in the usual 

 manner. 



Experiment v. 



At start 

 After 6 days.. 

 After 30 days. 



100 bacteria became at 22 c 



Soil incubated at 15°-20° 



unboiled 

 extract. 



35,000 



9,000 



420 



boiled 

 15 min. 66 min. 



129,000 



34,000 



6,000 



476,000 

 78,000 

 24,600 



incubated at 28°. 



unboiled 

 extract. 



35,000 

 1,500 

 3,900 



boiled 

 15 min. 60 min. 



129,000 



12,000 



9,000 



476,000 ! 370 

 43,000 i 390 

 17,800 ! 194 



