180 BACTERIOLOGICAL DIAGNOSIS. 
A great advantage of this method is that it does away 
with the necessity for any elaborate process for the 
sterilisation of the skin. The authors quoted above 
found that the results which they obtained were as good 
after simple cleansing of the skin with soap and water 
as after the use of antiseptic dressing. Nor is this to 
be wondered at when we think of the very small chance 
of any bacteria being carried through the skin and 
subcutaneous tissues into a vein by a very fine and 
sharp needle. 
The advisability of employing some such method in 
which the blood is drawn directly from a vein in place 
of the simple skin puncture is very apparent from the 
researches of Kihnau (‘“ Zeitschft. f. Hyg. and Infct.,” 
1890), who made parallel series of experiments by the 
two methods. He found that in cases in which the 
blood drawn directly from the vein remained sterile, 
growth (mostly streptococci or staphylococci) occurred 
in as many as ninety per cent. of cultures inoculated 
from skin punctures though the most careful antiseptic 
precautions were used. 
EXAMINATION OF BLOOD BY CULTURAL 
METHOD. 
This is a matter which is best carried out in a proper 
laboratory by an expert. If the practitioner attempts 
to carry it out for himself his best plan is to make a 
series of inoculations on the surface of agar.* The tubes 
* The ideal method is to make the inoculation directly into a large 
quantity of broth and to make sub-cultures on agar later. This 
method has the advantage that the blood becomes largely diluted, 
so that any bactericidal substances which it may contain are less 
likely to injure the bacteria. It is, however, rather more difficult. 
