New York Agricultural Experiment Station. 193 



Dunkirk fine sand. — The results of several tests in Dunkirk fine 

 sand are given in Table VI. Three of the four samples of this sandy 

 soil taken while frozen show distinct evidence of an increase in the 

 germ content similar to that occurring in clay. The one sample from 

 the cultivated portion taken on February 27th, shows the extremely 

 high count of 95,000,000 per gram. This is a very interesting fact 



Table VI. — Bacterial Counts of Field Soil. 

 Samples of Dunkirk fine sand. 



when the ordinary low count in this soil under normal conditions is 

 noticed. It is impossible to tell, however, whether such a great 

 increase in numbers is usual in this soil or is an isolated case to be 

 found only in this one sample. 



DISCUSSION. 



In general, the results here obtained verify the previous results 

 but do not explain them. They show that bacteria apparently 

 increase in numbers in frozen soil when all possibility of their being 

 carried up from lower depths is excluded. This increase seems to 

 depend on the low temperature or upon freezing rather than upon 

 an increase in soil moisture. 



There is still some possibility, however, that the increase may not 

 be an actual multiplication. Bacteria probably occur in the soil, 

 to some extent, in masses that are too firmly bound together to be 

 broken up by the shaking given the soil when it is diluted for plating. 

 In such a case each colony developing on the plates represents either 

 an isolated organism or an aggregate of two or more bacteria. It is 

 entirely possible that the freezing may break up these masses and 

 thus increase the plate count without adding to the actual number 



13 



