DETERMINATION OF ORGANISMS. 



47 



RELATION OF 20° AND 3 7° COUNTS IN SAMPLES OF WATER FROM APPAR- 

 ENTLY UNPOLLUTED SOURCES. 

 (Winslow and Nibecker, 1903.) 



Source of Samples. 



Gelatin 

 Plates 



3 CD 



5= S 



Litmus- 



lactose- 



agar 



Plates, 37' 



si 



s 



Dextrose Broth 

 Tubes. 



3 5 

 2 



I? re 



Cambridge supply (tap) 



Wakefield and Stoneham supply 



(tap) 



Lynn supply (tap) 



Brookline supply (tap) 



Plymouth supply (tap) 



Peabody supply (tap) 



Dedham supply (tap) 



Newbury port supply (tap) 



Salem supply (tap) 



Taunton supply (tap) 



Sharon (well) (tap) 



Medford supply (tap) 



Milton supply (tap) 



Westerly, R. I., supply (tap). . . 



Brooks 



Driven wells 



Springs 



Ponds fed by brooks 



Melted snow 



Pools in fields 



Pools in woods -. 



Roadside pools 



Stream, Blue Hill Reservation. . 



Flow from rocks 



Ponds fed by springs 



Drainage from manured pasture. 



Swamps 



Rain-water after twelve hours' 



heavy fall 



Shallow well in Lynn woods. . . . 



Totals 



7 

 6 

 1 

 6 



3 

 6 

 6 



5 



4 



3 



S 



2 



1 



61 



15 



3 2 



IS 



94 



59 

 16 



35 

 141 



3.717 

 36 



232 



13 



738 



5=4 



4,700 



223 



18 



294 



167 



47 



188 

 1.235 



269 



15 



15 



15 



12 



9 



15 

 6 



3 



183 



45 



95 



45 



3 

 66 



65 



3° 



3 



6 



259 



775 



41 



38 



