PREFACE. 



No practitioner who wishes to do his best for his 

 patients and to promote his own interests can afford to 

 neglect any means of clinical investigation which may 

 help him to arrive at a correct diagnosis, and offer hints 

 as to prognosis and treatment. Pre-eminent among the 

 more recent methods of investigation are those which 

 are applied by the bacteriologist ; and it is no exaggera- 

 tion to say that in many of the infective diseases a 

 diagnosis which is made without a bacterioscopic 

 examination is either mere guess-work or can only be 

 made so late that the patient has suffered unnecessarily 

 in health and the practitioner in prestige. In many 

 cases, however, the investigation requires a consider- 

 able amount of technical skill and access to a well- 

 equipped laboratory; the former may perhaps be pos- 

 sessed by the rising generation (for bacteriology is now 

 an integral part of the medical curriculum), but it 

 would be unfair to expect every medical man to add 

 the latter to his already expensive equipage. But in 

 many cases the diagnosis can be arrived at by very 

 simple means a few slides, cover-glasses, and stains, 

 a good microscope (which ought to be considered as 

 essential as a stethoscope), and a very moderate amount 

 of technical skill will often enable the practitioner to 

 arrive at correct diagnosis in a very short time. This 

 little book is intended in the first instance to show 

 exactly when this may be done, and to provide clear, 

 succinct, and full descriptions of simple methods which 

 may be employed. The descriptions of the operations 

 which the practitioner can carry out for himself are 

 mostly written in the imperative mood, and are in- 

 tended to be referred to constantly and carried out, step 

 by step, during the process. They represent the in- 



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