vl PREFACE. 
structions which would be given by a teacher when 
watching a beginner making a simple bacteriological 
examination for the first time. 
It cannot be too strongly urged that the practitioner 
should make the examination for himself whenever it is 
possible for him to do so. The report which is sent 
from a public laboratory may often be of very consider- 
able value, but it must be remembered that the bac- 
teriologist can only supply facts, and the inferences 
which may be drawn from those facts will largely 
depend upon a knowledge of the patient’s clinical 
history and the method in which the material was 
obtained. The bacteriologist is too often in the posi- 
tion of a detective who has to unravel a mystery from 
observations made by other people, and has no oppor- 
tunity of making investigations for himself. A bacterio- 
logical examination which is made by one person and 
interpreted by another, or which is made on material 
which has passed through more hands than one, loses 
much of its value; and an investigation made on the 
spot may be more valuable than one made by a bac- 
teriologist of far greater experience at a distance. 
The methods which are described in this little book 
are not in all cases the ideal ones, and in some cases 
they are somewhat different from those which are 
generally used, but they are simple and efficient. Of 
course, the simple examinations which are described 
here would frequently be supplemented by more com- 
plicated cultural ones by a trained bacteriologist. 
The methods described here have been taught in 
the post-graduate classes which were initiated some 
two years ago in the University of Birmingham; 
these have already been attended by about a hundred 
practitioners, who have found these methods of great 
assistance to them in their everyday practice. They 
have been selected so as to provide examples of some 
of the more important operations in constant use in 
the bacteriological laboratory. The author takes this 
opportunity of expressing his cordial thanks to Professor 
Leith for his kind suggestions as to the general scope 
of the book. 
