PREFACE TO THE SECOND EDITION. 



It is now well-nigh a year ago since my publisher 

 telegraphed to me in India, requesting permission to reprint, 

 on account of the entire first edition being "sold out," and 

 I feel that some explanation is required of what might 

 appear undue delay in meeting the demand for further 

 copies. I felt at once, however, that a mere reprint was 

 out of the question, though I had little idea of the magnitude 

 of the tOiSk before me. The first edition had served its 

 purpose in providing workers on the subject with a handy 

 compilation of existing literature, for it neither was, nor 

 professed to be, in any sense original ; but a year's work in a 

 very malarious and much mosquito-beridden country had 

 furnished me with material on which to found personal con- 

 clusions on many points, and so much had been written by 

 other students of the subject, in all parts of the world, that 

 it was clear that no mere compilation would now^ serve the 

 purpose. The statements as to the anatomy of the adult 

 insect, reproduced from various authors, in the first issue, I 

 had already found were inaccurate in many points, and the 

 chapter on that subject is now the result of a couple of 

 months of constant work with the microtome, and by dis- 

 section. So much had been said and done on the question 

 of malarial prophylaxis, that it was clear that a separate 

 chapter on the subject was absolutely essential, and the net 

 result of these, and other changes, was that when the 

 scattered notes came to be put together, hardly a paragraph 

 of the old matter of the first, or general, portion of the book 

 remained in its original form, and it had been, for all 

 practical purposes, rewritten, 



I hoped, however, that the second, or systematic, por- 

 tion would only require bringing up to date by inserting in 



