t 739 1 



Chloride of zinc ... ... i to 250 



Lactic acid ... ... i to 125 



Carbonate of sodium ... ... i to TOO 



Alcohol i to 10 



CHAPTER CXXVI. 



AGRICULTURAL BACTERIOLOGY. 



TDROFESSOR Hankin of the Agra Bacteriological Laboratory 

 reported a few years ago, that the water of the Ganges 

 and the Jumna contained nearly a thousand microbes to the 

 cubic centimetre, that is, in about a quarter of a tea spoonful. 

 In European bacteriological laboratories they usually find one 

 to two hundred thousand microbes per cubic centimetre of 

 water. Even ordinary good drinking water usually contains 

 about 100 microbes to the cubic centimetre. As is the water, 

 so is the air and the earth teeming with microbes. Generally 

 speaking they are harmless ; but occasionally the air, or the 

 water, or milk, or even the earth, teems with germs which are 

 capable of producing epidemics. A cubic yard of country air 

 contains from 50 to 350 germs, while a cubic yard of city air, 

 contain over 2,000 germs, and the air inside houses contains 

 over 5,000 germs per cubic yard, specially where there is 

 carpet or mat used in the rooms. An ounce of street dust may 

 contain over 30 million living germs. The superficial layers 

 of soil also teem with bacteria. There may be hundreds of 

 thousands in a single grain of superficial soil, but at a depth 

 of 10 to 20 ft, there are no microbes. On the top of high moun- 

 tains and in mid-ocean the air is free from microbes, and 

 spring water is also free. The usual source of microbes is, 



