ISO LECTURE IV. 



its anatomy. In the fluke also, whose 

 food is gall, and which lives and multiplies 

 in the biliary ducts of sheep, we see the 

 eall imbibed from an orifice into a ves- 

 sel which sends off branches to all parts 

 of the animal, apparently becoming its dis- 

 tributive or nutrient vessel. If this be true, 

 bile, which is formed from the blood of the 

 sheep, is reconverted into the blood of the 

 fluke, and forms the fleshy substance of 

 this animal. It was one of the distin- 

 guishing characters, and greatest perplex- 

 ities of Mr. Hunter's Physiology, that he 

 asserted vessels could modify their contents, 

 so that a kind of digestion may be said to 

 take place every where by the immediate 

 action of the vital powers. The structure 

 of the last mentioned animals, as far as it 

 is known, is exhibited in the collection ; 

 and the preparations were given to Mr. 

 Hunter by Mr. Carlisle, who made them 

 whilst a student. 



The hydatid seems to be nourished in 

 like manner. Analogy would induce us to 

 believe that it was noiuished, like vege- 



