viii AUTHOR'S PREFACE. 



Professor H. E. Richter, of Dresden, and Dr. A. von Graefe, of 

 Berlin. But above all, I must thank my friend Dr. F. A. Zenker, 

 of Dresden, for sending fresh specimens of Trichina spiralis, fresh 

 intestinal mucus, with living males and females of Oxyuris 

 vermicularis, and spirit specimens of Trichocephalus . Lastly, I 

 may also express my best thanks beforehand to all those who will 

 have the goodness to assist me by forwarding rare parasites, 

 especially living Trichocephali, which may be sent long distances 

 in white of egg, and will remain alive for six or eight days ; I 

 must also beg all who are interested in this branch of science, to 

 assist me by sending me rare parasites, especially those found on 

 the human body (in spirit or white of egg), for examination and 

 future use, either as loans or gifts. 



Finally, I shall be thankful for any sound criticisms or correc- 

 tions founded upon personal study. 



And thus I present to the public this book, with its preface 

 (vorreden), which deserves the name of a preface more than most 

 productions of the kind which, in homage to the fashion of the 

 day, are written after works have been published in parts, and 

 which might rather be called postscripts (nachreden). The post- 

 script I leave to others, may it be a good one. 



THE AUTHOR. 



