202 BACTERIOLOGICAL METHODS 



the staining properties and the morphological characteristics of 

 the different kinds of bacteria and of other organisms. Cultural 

 methods may be desirable for purposes of identification. 



The bacteriological testing of ampuls and all medicamenta in- 

 tended for hypodermic, intravenous and intramuscular use is 

 reduced to great simplicity. Since these substances must be 

 absolutely sterile, the finding of living bacteria (by the plating 

 method) would be proof that they are unfit for use. It must be 

 borne in mind, however, that cloudiness in ampuls (containing 

 substances which should be clear) does not necessarily indicate 

 bacterial contamination, as this condition is frequently the re- 

 sult of chemical change, possibly occasioned by the alkalinity 

 of the glass used in making the ampuls. However, all ampuls 

 which show cloudiness when they should be entirely clear are 

 to be rejected, even though no hving organisms are present. 

 Oils, salves and plasters may be examined directly (microscopic- 

 ally), noting in addition to bacteria and other living and dead 

 organisms, possible decomposition changes in oils and fats, as 

 indicated by the presence of the characteristic fat crystals. For 

 plating, oils may be emulsified with measured quantities of the 

 hquefied gelatin or agar media and measured quantities poured 

 into Petri dishes; or definite quantities (o.i cc, o.oi cc, o.ooi cc, 

 etc.) may be planted into the Petri dishes in the regulation man- 

 ner and the hquefied gelatin or agar poured over it and spread. 

 Incubate for from 3 to 4 days at a temperature of 20° C. and 

 count the colonies formed. Plasters and salves may be plated 

 by hquefying them at a temperature not to exceed 40° C, 

 making the desired dilutions with sterilized olive oil. 



20. The Microscopical and Bacteriological Examination of Syrups 



Syrups are very important products extensively used in 

 medical and pharmaceutical practice and at the soda fountain, 

 and for practical purposes may be grouped as follows: 



