k 



LECTURE IV. 183 



tables, by absorption from without, Of its 

 organization however we are perfectly igno- 

 rant, for no evident structure can be dis- 

 cerned, even by the aid of the microscope. 

 These animalcules are found in the na- 

 tural cavities, or in those formed in conse- 

 quence of disease, in the bodies of other 

 animals. We meet with them in the abdo- 

 men, in bursse mucosae, and in cysts in 

 the brain, liver, and other organs. The 

 form of one species is a globular or oval 

 bag, which has an undulatory motion, when 

 put into tepid water. The bag contains a 

 transparent fluid. Young hydatids form 

 upon the bag, are detached when very small, 

 float about in the liquor of the cavities in 

 which they dwell, to grow and to multiply 

 as their parents have done. Nov/, in a phy- 

 siological point of view, we must consider 

 hydatids to be nourished by absorption 

 from without, or suppose the bag to be a 

 digesting ckvity, though no aperture is dis- 

 cernible. In the department of the Museum 

 allotted to display the structure of the di^ 

 gestive organs, Mr. Hunter has first put up 

 some hydatids, as if to mark tixe uncef-^ 



N 1 



