FARM DAIRYING 



So potent is the power of reproduction that one 

 germ may become two in half an hour, and the 

 progeny from just one bacterium may number 



At a is represented a single 



germ; at b is represented the 



' this germ in 24 hours 



at a temperature of 



c is represented the 



„ iv>iV,>y!-iY;',T'«"; -."'tj i'i"s>-'v "» t^^ same germ in 34 

 A B '/r-f^'i'Vol^teul-^vvVVju^;-^^ hours if the milk were kept at 



70 F. At 50 the multipli- 

 cation was five-fold, at 70° it 

 was seven hundred and fifty fold. 

 (After Conn.) 



DIAGRAM SHOWING THE EFFECT OF TEMPERATURE ON 

 THE KEEPING OF MILK 



over sixteen million, five hundred thousand in 

 twenty-four hours. However, they do not go on 

 increasing forever at such a rapid rate; the food 

 supply gives out, or they cannot thrive in an ex- 

 cess of their own by-products — lactic acid, for 

 example. 



Sometimes spores develop inside the germ cell 

 and these have wonderful power of resistance 

 against heat, some surviving even the boiling point, 

 and many other adverse conditions. Freezing 

 does not destroy bacteria. 



Three things are necessary for bacterial growth 

 — food, moisture, heat. An absence-of any one 

 of these renders the germs dormant. We cannot 



[159] 



