X PREFACE 



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, and if not, to call in the services of an expert pathologist. 

 The report which is sent from a public laboratory may often be of 

 very considerable value, but it must be remembered that the 

 bacteriologist 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 

 position of a detective who has to unravel a mystery from obser- 

 vations made by other people, and has no opportunity of making 

 investigations for himself. A bacteriological 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 bacteriologist 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. 



No apology will be made for the numerous repetitions which 

 will be found in this book. They are essential to its scope, which 

 is to give clear accounts of the processes with as little reference to 



