^PREFACE TO THE SECOND EDITION 



The circumstances that led to the first publica- 

 tion of this book as well as its general scope and 

 character are explained fully by Dr. Ricketts in 

 the preface to the first edition. The book met 

 with such favorable reception that the edition was 

 exhausted while the demand continued active. 

 This indicated that an actual want had been met 

 and so it was determined to publish a new edition, 

 revised and enlarged, and for some time previous 

 to his greatly lamented and untimely death Dr. 

 Ricketts gave freely of his already heavily taxed 

 energies and strength to the work of revision. 



Surely a simple word or two in tribute to the 

 memory and achievements of Dr. Ricketts are not 

 out of place at this point. He died in Mexico City, 

 May 3,, 1910. at the age of 39, from typhus fever 

 which he was investigating with splendid success 

 when he was taken ill. Thus a noble and inspiring 

 career of large service to humanity and of rich 

 promise came to a sudden and heroic end. During 

 his short but intensely active life as an investi- 

 gator in the field of infectious diseases Dr. Rick- 

 etts made important contributions of permanent 

 value to medical science : he greatly advanced our 

 knowledge of blastomycosis ; he solved the most 

 important problems in the cause and transmission 

 of Rocky Mountain spotted fever, and discovered 

 that this disease is conveyed by a tick (Derma- 

 cenior venustus and D. modest us), in which the 



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