vi PREFACE 



dissection should, in the author's opinion, be left to the teacher, who 

 should certainly be the one best qualified to fornnilatc the course adapted 

 to his needs. No general outline, therefore, as to laljoratory methods 

 has been attempted. 



If, as has been said, orighiality is not the best reconnnendation for a 

 work of this kind, the author feels quite sure that its defects cannot to 

 any great extent be attributed to that source. His observations in the 

 field and laboratory have been utilized in the preparation of the book, 

 but contribute nothing to its pages that is advanced or aggressively 

 critical. Excluding the first three chapters, so much of the sul)ject- 

 matter has been drawn from the published results of the labors of others 

 that the numerous sources cannot well be enumerated here. Acknowl- 

 edgments are especially due to bulletins and articles upon various topics 

 of parasitolog}' written by workers in federal and state bureaus of ex- 

 perimental research. Other sources which have been relied upon and 

 freely used are: 'M. Neveu-Lemaire's Parasitologic des Animaux Domes- 

 iiques; Herms' Medical and Veterinary Entomology; Riley and Johann- 

 sen's Handbook of Medical Entomology; Calkins' Protozoology; Neumann's 

 Parasites and Parasitic Diseases of the Domesticated Animals; Bi-aun's 

 Animal Parasites of Man; The Journal of Parasitology; The American 

 Edition of Hutyra and Marek, and Osborn's Economic Zoology. 



The author wishes to express his sincere appreciation and thanks to 

 his laboratory coworker. Dr. Fred Boerner, Jr., for his assistance in the 

 collection of specimens and in the examination of pathologic material; 

 also to Dr. William J. Lentz for his reading and valuable criticism of 

 parts of the manuscript, and to Dr. C. P. Fitch for his helpful suggestions 

 as to sources of reference. 



Illustrations for a work of this character will ])e an aid to the text in 

 proportion as they are exact and well chosen. For the study of mor- 

 phologic characteristics photographs of actual specimens are often too 

 obscure in detail, and accurate drawings or line sketches are, as a rule, of 

 greater service. It will be observed that man}' of the figures in this 

 book are taken from publications issued by the United States Depart- 

 ment of Agriculture. Probably no better drawings of these subjects have 

 been produced, and the privilege granted to use them is esteemed as a 

 helpful favor of much value to the work. In this connection the author 

 would especially express his gratitude to Dr. L. 0. Howard. Chief of the 

 Bureau of Entomology, to Dr. John R. ]\Iohler, Chief of the Bureau of 

 Animal Industry, to Dr. Herbert Osborn, to Dr. Howard Crawley, and 

 to Dr. B. H. Ransom. Finally, thanks are due to Dr. W. H. Hoedt of 

 Philadelphia, for his skill and interest in preparing the photomicro- 

 graphs and many of the drawings. 



B. ]\I. U. 



Philadelphia, Pa. 



