PREFACE TO SECOND EDITION 



The success of the first edition of this book, and in particular 

 the numerous proofs I have received that it has been of value to 

 those for whom it was intended — that is, to practitioners who are 

 without training in pathology, and who want a simple guide to 

 refer to — has encouraged me to add to it somewhat, though 

 without altering its general scope. 



The additions to the bacteriological portion are mostly concerned 

 with the examination of materials from special parts of the body — 

 mouth, conjunctiva, etc. — which were insufficiently dealt with in 

 the first edition, and are treated on simple lines ; in most cases 

 the diagnosis by microscopical methods, and in particular by the 

 application of Gram's stain, is given. 



The haematological portion is almost all new, and is written in 

 response to numerous requests for a practical guide to blood 

 examinations, especially their application to the diagnosis of 

 disease. I have attempted to deal with the subject on the same 

 lines as the bacteriological portion — that is, to explain the con- 

 ditions under which a certain examination is indicated, the method 

 employed (in full detail), the deductions to be drawn from the 

 results obtained, and the cautions necessary in interpreting them. 

 It is in respect of these interpretations of blood-counts that I 

 think such a guide as this is most urgently required, as I find 

 there is a lamentable ignorance of the conditions under which 

 blood-counts are required and the methods of drawing deductions 

 from them. The result is that these examinations are often made 

 unnecessarily or omitted when they should be made, that the 

 diagnosis is not helped, and the clinical pathology is not appre- 

 ciated as it ought to be. The great stumbling-block has been 



