rOXTON-FIRBT ON THE H.EMATOZOA. 355 



surrounding the vessels, hut tin's does not appear very likely to he tlio 

 case. Specimens of entozoa, discharged through the urethra of a young man, 

 were some years ago exhihited hefore the Entomological Society of London. 

 Ainong the human hannatozoa, the most important is the variety hefore 

 mentioned ( Distoma hcematohiitmj, which has only heen observed in Egypt. 

 The liver-fluke (Distoma liepaticum) has occasionally been found in tho 

 interior ramifications of the portal vein. Those ha3matozoa found in tumours 

 and other morbid excrescences, appear undoubtedly to have been conveyed 

 there by the circulating blood. The liver-flukes (Distoma liepaticum) which 

 I examined, were taken in prolific abundance from the veins in the liver of 

 a sheep. I do not remember ever having seen so many taken from one 

 animal, as in this instance. In colour they were of a very dark broA\ai, 

 almost approximating to a black tinge, and soon showed no symptoms of 

 life when taken for a few minutes from their proper element. It does not 

 appear from all I can hear on the subject, that these parasitic entozoa, by 

 their presence often in great quantities in the arteries and veins of a sheep, 

 affect the health of the animal to any appreciable degree. This may, in part, 

 be attributable to the suctorial appendages of the parasite, Avliich are 

 subservient to the functions of an oral aperture or mouth, and cannot 

 therefore in any way injure the delicate lining of the hsematoid ducts and 

 veins. It may not perhaps be generally known that the very common 

 disease among sheep, known as giddiness, or water in the brain, proceeds 

 from the formation of a hydatid ( Polycephalas ovinusj in the brain, and is 

 of frequent occurrence in oxen, sheep, and other ruminants. It often occurs 

 in one of the lateral ventricles of the encephalic mass, and occasions a kind 

 of vertigo, the poor animal turning round and round in a lateral direction, 

 generally on the side where the afi'ected part is afterwards found to be 

 situated. Hydatids are a species of entozoa, and were first discovered by 

 Hartman in 1686, to be distinct parasitic animal organisms. In appearance 

 the hydatid, or acephalocyst (Greek, headless bag), is a mere cystic tumour, 

 filled mth a fluid that is always, in a proper hydatid, colourless and clear as 

 crystal. It ranks as the most simple of the entozoa. 



Gretcelthorpe, near Ripon. 



