viii AUTHOR'S PREFACE. 



the question, it was no part of my plan to make the book into a 

 collection of Pathological curiosities by the detailed narration of 

 numerous cases. Those who desire such a record are referred to the 

 pages of Davaine, " Traite* des entozoaires et des maladies vermineuses," 

 a work which only partially justifies its title, since the Zoological 

 portion is very incomplete, and by no means up to the level of our 

 present Helminthological knowledge. 



In conclusion, I must point out that the earlier sheets of the 

 German Edition of this volume have already been published six years, 

 in the course of which investigation has been active, and much has 

 been added to our sum of knowledge. Whilst revising the present 

 translation, I have striven, by the addition of notes and by modifica- 

 tions of the text, to give an account of this progress, and hope that 

 nothing of importance has been omitted. 



In the original compilation of this work I thought primarily of 

 Gennan readers, and hence it bears throughout traces of its origin. 

 But the quiet activity of the man of science is everywhere a portion 

 of the universal work of that spirit whence the history of culture 

 took its origin, and so may my book for the profit of the whole pass 

 over the bounds of its home, and win for itself new friends in other 

 lands ! 



In conclusion, it affords me very great pleasure to express my 

 hearty thanks to Mr. W. E. Hoyle, the Translator of my work, for the 

 conscientious and in every way satisfactory manner in which the 

 English Edition has been prepared. 



RUDOLF LEUCKAKT. 



LEIPZIG, September 1886. 



