PREFACE 



MY introductory treatise on the Entozoa having long been 

 out of print, it occurred to me that instead of attempting 

 another edition it would be better to write an entirely new 

 work, employing only such fragmentary portions of the old 

 treatise as would harmonise with the far wider design I have 

 now in view. Whilst, therefore, I have freely utilised a 

 selection of the illustrations given in the elementary volume, 

 comparatively few of its pages have been incorporated in the 

 present work. 



Dealing with parasites and parasitism after a manner not 

 hitherto attempted I have purposely omitted minute anatomical 

 descriptions, and, with rare exceptions, I have avoided the 

 introduction of clinical details. While bringing to a focus the 

 records of, and principal references to, a widely scattered, intri- 

 cate, and voluminous literature, it has been my chief endeavour 

 to supply abundance of original matter of a kind that cannot 

 be found in the columns of any existing treatise. Whether I 

 have succeeded or not the experienced helminthologist alone 

 can judge. He, at all events, will perceive that the summary, 

 though compressed within the space of a moderate-sized octavo, 

 can only have resulted from sustained effort. 



This treatise is not professional, that is to say, it does 

 not concern itself with therapeutics or the curative treatment 

 of parasitic affections; yet it introduces and helps to solve 



