X teanslatoe's preface. 



Thanks to the writings of Cobbold and others, out language 

 already possesses equivalents for most of the technical terms in this 

 work, but it has always appeared to me that it would be very 

 desirable to distinguish between the transference of a parasite from 

 one host to another, and its movement from one organ to another in 

 the same host. Hitherto the word " migration " has been used in both 

 these senses, but in the present work I have confined it entirely to 

 the former signification, and adopted " wandering " to express the 

 passage from one organ to another. 



The Second Volume of the original is now being revised by the 

 Author, preparatory to the issue of a new edition; he has kindly 

 undertaken to forward the proof sheets of this for translation, so that 

 the English version may pass through the press pari passti with the 

 German, and be published simultaneously with it. 



In conclusion, I must fulfil the pleasant duty of expressing my 

 great indebtedness to my friend Mr. J. Arthur Thomson, M.A., who 

 has acted as my assistant throughout the progress of the work. 

 Upon him much of the more laborious part of the work has fallen, 

 and without his painstaking and intelligent co-operation the present 

 translation could not possibly have been completed in the time which 

 has elapsed since it was undestaken. 



WILLIAM E. HOYLE. 



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