m OF HYDAxros. 



" Of the Sac of Hydatids. 



'"^Tlie sac of the hydatid seems to be formed of 

 condensed cellular substance, and the thickness of 

 the sac generally bears a ratio to its size and situa- 

 tion. This sac is secured in its place by several 

 bands of cellular substance, which pass between it 

 and the bowels, within which it is lodged, and in 

 the abdomen it is covered by the peritonaeum. 



^* The thickness of the sac of an hydatid is in 

 proportion to its size ; though there is considerable 

 difference in this particular, the sac being thickest 

 where it is most exposed : thus when the greater 

 part of the sac is surrounded by the substance of a 

 bowel, as of the liver for instance, that part only of 

 the sac, which is exposed, is of a considerable thick- 

 ness, and is sometimes cartilaginous, or covered by 

 layers of bone. 



'' I have observed that the inner surface of the sac 

 is by no means uniform, but always somewhat ir- 

 regular, and lined by a very thin layer of fat. A 

 glairy gelatinous liquor is also interposed between 

 the sac and the hydatid, which prevents the hyda- 

 tids from being injured by friction. The sac of a 

 large hydatid is sometimes divided into compart- 

 ments, which serve to prevent the smaller hydatids, 

 contained within the opposite ends of the sac, from 

 pressing on each other." 



