14 PARASITES OF MAN 



SECTION I. TREMATODA (Flukes). 



Fasciola hepatica, Linneus. The first form I have to con- 

 sider is the common liver fluke. The part this entozoon plays 

 in the production of disease will be fully stated when treating 

 of the parasites of the sheep and other ruminants. About 

 twenty instances of its occurrence in the human body have been 

 recorded. It has been found beneath the skin in the sole of 

 the foot (Giesker), and also under the scalp (Harris), and 

 behind the ear (Fox). Its more frequent seat is in the liver 

 and gall-ducts (Pallas, Brera, Bidloo, Malpighi) and gall-bladder 

 (Partridge). The alleged cases by Bauhin, Wepfer, and Chabert 

 are spurious, as is probably also that given by Mehlis. DuvaPs 

 case appears to be genuine, but the occurrence of the worm in 

 the portal vein was accidental. Dr Murchison has recorded a 

 case, occurring at St Thomas's Hospital, where a solitary 

 specimen was found in the liver. Dr H. V. Carter also met 

 with the worm in a young Hindoo. 



In the second half of the present work I shall reproduce 

 Blanchard's admirable figure of the sexually mature worm 

 (Fig. 61), accompanied by a categorical statement respecting 

 the known facts of development. In this place, however, I 

 may observe that the cases recorded by Giesker, Harris, and 

 Fox had clearly pointed to the circumstance that the higher larv;>> 

 of this fluke must be armed cercaria6, otherwise they could not 

 have bored their way through the human skin. As we shall see, 

 Dr Willemoes-SuhnVs investigations have furnished evidence 

 as to the truth of this supposition. For anatomical details I refer 

 to my introductory treatise. In the adult state the liver fluke 

 has been known from the earliest times. We have clear 

 evidences that it was described by Gabucinus in the year K 17, 

 and also subsequently by Cornelius Gemma, who, in a work 

 published some thirty years later, refers to an epizootic disease 

 prevalent in Holland during the year 1552, and which was very 

 justly attributed to the parasite in question. After this date 

 many writers described the liver fluke more or less accurately, 

 and entire volumes were devoted to the consideration of the 

 formidable disease which it occasions. The nomenclature of 

 the parasite has been a subject of controversy. Amongst 

 naturalists in general the common liver fluke is often de- 

 scribed under the combined generic and specific name of 



