136 BACTERIOLOGICAL DIAGNOSIS. 
When the abscess has been opened a considerable 
quantity of pus should be allowed to flow out, and the 
sterilised pipette is then to be passed through the 
incision (care being taken to avoid contact with its 
sides) and the pus carefully sucked up into the bulb. 
The fluid thus obtained may be used to inoculate 
cultures there and then, or both ends of the pipette 
may be sealed in the flame and the pipette sent toa 
laboratory. 
Tue EXAMINATION OF Pus. 
The organisms which may cause pus are extremely 
numerous, the most important being streptococci, 
staphylococci, the pneumococcus and the gonococcus, 
the bacilli of typhoid fever, tuberculosis, and glanders, 
the bacillus coli communis, the bacillus pyocyaneus 
(the organism which produces blue pus), and the fungus 
of actinomycosis. Inthe majority of cases the organism 
which is present in a given sample of pus can be 
determined by a microscopic examination of films 
prepared in the usual way and stained by a simple 
stain, such as carbol-thionin. A specimen should aiso 
be stained by Gram’s method and the results compared. 
When cultural examinations are required they had 
better be carried out in a public laboratory. If the 
practitioner should desire to carry them out for himself 
he had better make stroke cultivations on agar in the 
manner described on page 22, and incubate them for 
twenty-four hours at the temperature of the body. The 
appearances of the colonies will be similar to those 
described as occurring in cultures made from the blood, 
to which the reader is referred. It is to be noted, 
however, that the gonococcus will not grow under 
