BACTERIOLOGICAL TECHNIC. 4, 



The essential requirements given under a, b, and c are obtained by filtra- 

 tion, neutralization, and sterilization, as will be more fully explained. Non- 

 liquefiable solid media, as potato, bread, squash, etc., must be clean, free 

 from Uving microbes and other organisms, and there should be a compara- 

 tively smooth exposed inoculating surface. These requirements are attained 

 by washing and otherwise cleansing, disinfecting, rinsing, and heat sterili- 

 zation (dry heat, steam or hot-water bath). 



The following are the more important media: 



A. Nutrient Bouillon. — 



Mix ingredients and boil for a few minutes. Filter 

 through filter paper. This bouillon may be modified 

 by adding glycerin (6 per cent.) and sugars, as dextrose, 

 saccharose, or lactoSe (i per cent.). 



B. Loeffler's Blood Serum. — Very largely used in 

 making diagnostic diphtheria bacillus cultures. In 

 many cities this medium, with sterilized cotton swabs, 

 in sterilized test-tubes, is furnished free to physicians 

 by the board of health. In cities and towns where this 

 is not done, the pharmacist should be prepared to fur- 

 nish the materials to the physicians. The medium con- 

 sists of 



Bouillon with i per cent. Glucose, 

 Blood Serum, 



I part. 

 3 parts. 



Fig. 19. — Culture 

 tube and swab tube 

 used by physicians in 

 the diagnosis of diph- 

 theria. The swab 

 tube should be long 

 enough to have the 

 entire length of swab 

 inside, not projecting 

 as shown in the fig- 

 ure. (Williams.) 

 The bouillon is prepared as above described, with i 



per cent, of glucose added. The blood serum can be obtained from calf, sheep, 

 ox, or cow, through the butcher or at the abattoir. Collect the blood in a clean, 

 sterile jar or flask, closed with cotton plug. Place on ice for twenty-four to 

 forty-eight hours, during which time coagulation has taken place; the serum 

 may then be siphoned off. The proper sterilization of LoefBer's serum re- 

 quires care. After the bouillon and serum are mixed, pour into test-tubes 

 and coagulate in a Koch-serum coagulator at a temperature of 80° C. Any 

 form of sterilizer may, however, be used. The essentials are that the tem: 

 perature should be raised very gradually and must be kept below the boil- 

 ing-point, and the tubes should be slanted at a degree which will bring the 

 medium close to the cotton plug, making what are commonly called tube 

 slants. After the medium is coagulated in the tubes it is sterilized frac- 



