326 METHODS OF ANALYSIS 



and count the number on another similar area. Count 5 such areas, preferably 1 

 from near each corner of the ruled portion of the slide and 1 from near the center. 

 Determine the average number of bacteria per area and multiply by 2,400,000 which 

 gives the number of bacteria per cc. If a dilution of 1 part of the sample with 

 8 parts of water instead of 1 part of the sample with 2 parts of water is used in 

 making up the sample, then the total count obtained as above must be multiplied 

 by 7,200,000. Omit the micrococci type of bacteria in making the count. 



BIBLIOGRAPHY. 



1 Z. anal. Chem., 1892, 31: 525; Conn. Agr. Exp. Sta. Kept., 1898, (II), p. 190. 



2 U. S. Bur. Chem. Bull. 13 (II), p. 165. 



3 Conn. Agr. Exp. Sta. Kept., 1898, (II), p. 187. 



* Winton. Microscopy of Vegetable Foods. 2nd ed., 1916; Vogl. Die wichtig- 

 sten vegetabilischen Nahrungs-und Genussmittel. 1899; Tschirch und Oesterle. 

 Anatomischer Atlas der Pharmakognosie und Nahrungsmittelkunde. 1900; Greenish 

 and Collin. Anatomical Atlas of Vegetable Powders. 1904; Greenish. Microscopical 

 Examination of Foods and Drugs. 2nd ed., 1910; Koch. Die Mikroscopische Ana- 

 lyse der Drogenpulver. 1900-08. 



' U. S. Bur. Chem. Circ. 68, p. 4. 



