224 



GENERAL MICROBIOLOGY 



pec ted the sample must be diluted. Use distilled water 

 for dilution flasks.) 



FIG. 48. 



FIG. 49. 



FIG. 48.^-A Model Dug Well Constructed to Avoid Microbial Con- 

 tamination of Water. (From Gerhard's Sanitation, Water 

 Supply and Sewage Disposal of Country Houses.) 



FIG. 49. A Shallow Driven or Tube Well. (From Gerhard.) 



5. To the melted agar shake (at 45 C.), add 100 c.c. 

 of the sample, using the volumetric pipette, and shake well 



