Parasites of the Liver. 35 1 



give a brownish color, the digestive canal is divided in two non- 

 ramified branches, narrowed toward their blind ends which extend 

 to the caudal fourth of the body. The ova are very numerous, 

 ovoid, brown, -^\-^ inch in diameter, with a larger operculum than 

 the distonia hepaticum. The yolk is often segmented before be- 

 ing laid. 



The embryo is globular and is covered with cilia on the ante- 

 rior third of the body only, and provided with a conical cephalic 

 borer. Its movements are less active than tho.se of the distonia 

 hepaticum embryo. The .successive stages of development are 

 supposed to be identical or nearly so in the two species. The 

 moluscous host is, however, not certainly known. The claims 

 for the planorbis marginatus (Willemoes-Suhm) and helix car- 

 thusiana (Plana) have been successfull3' controverted. 



Habitat. The distoma lanceolatum lives in the gall ducts of the 

 sheep, ox, goat, red and fallow deer, rabbit, hare, pig, a.ss, dog, 

 cat and man. It usually occurs in company with the distoma 

 hepaticum, though in smaller numbers, and it has been held to be 

 much less injurious owing to the absence of cutaneous spines. It 

 has, however, the .same blood-sucking habit, and when equally 

 numerous must, in this respect, be correspondingly hurtful. 



Accessory causes. From time immemorial wet seasons and inun- 

 dations have been observed to coincide with great lo.sses in flocks 

 and herds, and though some of these outbreaks doubtless came 

 from different parasitisms and infectious diseases, yet in the light 

 of modern experience much was probably due to the liver fluke. 

 Fitzherbert even mentions the 'flokes' as associated with the drop- 

 sies and jaundice as early as 1532. Wet seasons and rot coin- 

 cided in 1628 (Bottani), 1761-2 (Demars), iSog-'io-'ii and '12, 

 90,000 sheep having died in 1812 in Nimes and Montpelier, and 

 100,000 in Aries (Huzard, Tcssier). In 1816-7 it was again 

 most de.structive in France and England (Huzard, Tessier, 

 Simonds), and again in France in 1820-29-' 30-' 53-' 54, and in 

 Kngland in i824-'30-'52-'53-'6o-'62 and '72. In 1824 Mr. Cramp 

 lost $15,000 worth of sheep in the small isle of Thanet in three 

 months (evidence in House of L,ords), and in 1830-31 England 

 lost 1,000,000 to 2,000,000 (Ed. Vet. Review). In 1833 the 

 Smithfield, London, .sheep market had on each market day 5,000 

 head less than the former average (Evid. in Ho. of Lords). In 



