EXAMINATION OF FLUIDS AND SOLIDS 179 



If the material under examination is suspected of being nocuous for guinea- 

 pigs, 2 cc. of it should be injected into the peritoneal cavity of a guinea-pig. 



EXAMINATION OF QUININE 



Quinine salts which are intended for hypodermic administration should be 

 examined for bacteria, especially the tetanus bacillus, as cases of tetanus follow- 

 ing the hypodermic administration of quinine have been reported. 



TECHNIQUE 



\ 



Place i Gm. of quinine in each of two flasks containing 1000 cc. of glucose 

 bouillon. Incubate at 37C. one flask in an aerobic atmosphere, the other in an 

 anaerobic atmosphere. Inspect daily, and if growth occurs centrifugalize 15 cc. 

 of the culture at high speed for 20 minutes, collect the bottom cubic centimeter, 

 and inject it subcutaneously into a guinea-pig. 



Subcutaneous injections of sublethal doses of an aqueous solution of the 

 quinine should also be made. 



EXAMINATION OF CAT-GUT 



Catgut is especially apt to contain tetanus spores before treatment and 

 occasionally does after attempts at sterilization by approved methods, hence 

 cat-gut must always be proved sterile before it is dispensed for use in surgery. 



TECHNIQUE 



Select several strands or packets from a lot and put in a large test-tube con- 

 taining about 50 cc. of glucose bouillon, incubate at 37C. in an anaerobic at- 

 mosphere. Inspect daily, and if growth does not appear in 5 days it is sterile. 

 Some tubes should also be incubated in an aerobic 'atmosphere, and if desired 

 guinea-pig inoculations may be made. 



EXAMINATION OF KETCHUP 

 ESTIMATION OF MOLDS 



A drop of the product to be examined is placed on a microscope slide and a 

 cover glass is placed over it and pressed down till a film of the product about o.i 

 millimeter thick is obtained. After some experience this can be done fairly well. 

 A film much thicker than this is too dense to be examined successfully, while a 

 much thinner film, necessitates pressing the liquids out, which gives a very un- 

 even appearing preparation. When a satisfactory mount has been obtained, 

 it is placed under the microscope and examined. The power used is about 90 

 diameters, and such that the area of substance actually examined in each field of 

 view is approximately 1.5 square millimeters. 



A field is examined for the presence or absence of mold filaments, the result 

 noted, and the slide moved so as to bring an entirely new field into view. This 

 is repeated till approximately 50 fields have been examined, and the percentage 

 of fields showing molds present are then calculated. Our experience has dem- 



