74 BULLETIN 51, U. S. DEPARTMENT OF AGEICULTUEE. 



contain millions of organisms. It is reasonable to conclude, there- 

 fore, that the earlier forms of such and similar eggs furnish large 

 numbers of bacteria, to the liquid j)roduct prepared from second- 

 grade food eggs. It is quite probable, also, that these earlier stages 

 of incipient sour eggs are a contributing cause to the presence of 

 appreciable numbers of B. coli in liquid Qgg of good quality. 



TECHNIQUE FOR THE BACTERIOLOGICAL EXAMINATION OF 



EGGS. 



METHODS USED FOR OBTAINING SAMPLES OF INDIVIDUAL EGGS 

 OPENED ASEPTICALLY IN THE LABORATORY. 



^1. Mercuric clilorid method} — The eggs were washed in running 

 water, treated for five minutes in a 1 to 500 or 1 to 1,000 mercuric 

 chloric! solution, and then rinsed with sterile water. The egg was 

 then placed, large end uppermost, in a suitable holder. A small open- 

 ing was made in the apex with sterile, fine-pointed forceps, about 2 

 square centimeters of the shell removed, and the membrane punc- 

 tured. About 2 CO of the white were then transferred with a sterile 

 pipette to a. sterile tared weighing flask containing small pieces of 

 sterile glass. The opening was made larger and as much of the white 

 as possible removed -with the pipette. "With a second sterile pipette 

 the vitelline membrane was ruptured, and about 2 cc of the yolk 

 transferred to another weighing flask. When it was impossible to 

 examine white and yolk separately, on account of disintegration, a 

 sample of whole e.gg was taken. 



B. Flaming method." — The egg was washed in running water, 

 rinsed in. sterile water, dried with a sterile towel, and placed, large 

 end uppermost, in a suitable holder. The top of the &gg was steril- 

 ized by flaming. A portion of the top was removed with fine-pointed 

 forceps and the contents of the ^gg dropped into a sterile salt- 

 mouthed 4-ounce bottle containing sterile glass. 



PREPARATION OF COMPOSITE SAMPLES OF EGGS OPENED COMMER- 

 CIALLY IN THE PACKING HOUSE. 



The details of the collection and handling of the samples are de- 

 scribed on page 39. AAHien the samples arrived in the morning, they 

 were examined immediately. When thej came late in the day, they 

 were put at once into a sharp freezer and held overnight. On ar- 

 rival at the laboratory the hard-frozen samples were placed imme- 

 diately in a water bath at 40° C. and allowed to remain, with frequent 

 shaking, until completely melted. After shaking the melted sample 

 vigorously for five minutes, about 3 cc were transferred with a sterile 

 pipette to a tared weighing flask. 



1 Samples 4001 to 4159, inclusive, and 3001 to 3030, inclusive, were obtained by this 

 method. 



2 Samples with numbers under 1,000 were obtained by this routine. 



