(>9S DISEASES OF THE LIVER. 



numerous, the liver is usually decidedly enlarged. Sacs, deep in the 

 organ, and surrounded by liver parenchyma, change the form but little : 

 very large sacs, or those near the surface, are generally elevated above 

 the liver, and cause decided deformity of the organ. Over the periph- 

 eral cysts the peritoneal covering of the liver is decidedly thickened, 

 and is attached to the parts around by firm pseudo-membranes. The 

 parenchyma of the liver is displaced by the parasites, and, when these 

 are large and numerous, it is extensively destroyed ; the parenchyma 

 still preserved not unfrequently appears very vascular, as a result of 

 partial congestions. The echinococcus vesicle itself is enclosed by a 

 hard fibrous capsule, which is formed by proliferation of connective tis- 

 sue, but may readily be removed from this. The envelope of the ves- 

 icle itself is a delicate, half-transparent membrane, resembling coagu- 

 lated albumen, which, by the microscope, is shown to consist of numerous 

 fine, concentric lamellae. If we open the vesicle, a clear serous fluid 

 escapes ; this almost always contains numbers of smaller vesicles. The 

 fluid contains about 15 parts of firm constituent to the 1,000 ; no albu- 

 men, but chiefly salts, mostly chloride of sodium, and, according to 

 Heintz^ 3 parts of succinate of soda to the 1,000. The daughter ves- 

 icles are like the mother sac ; they are as large as a hemp-seed or a 

 large hazel-nut. The larger ones float about freely in the mother sac ; 

 the smaller ones are firmly attached to its inner wall. The grand- 

 child vesicles, which are only found in the larger daughter vesicles, are 

 usually about the size of a pin's head. On careful examination, we 

 may discover a whitish, gritty coating on the inner surface of the 

 mother, daughter, and grandchild vesicles. The microscope shows 

 this to be a colony of young, immature taeniae or scoleces. The indi- 

 vidual animals are about \ mm. long, and \ mm. broad ; they have a 

 thick head, with four suckers, and a snout which is surrounded by a 

 double row of hooks. The head is separated by a constriction from 

 the short body, in which there are numerous round and oval chalk con- 

 crements. The head is generally drawn into the body. The animals 

 are then usually round or heart-shaped, and the circle of hooks is in the 

 middle. At the posterior end of the body is a short pedicle, by which 

 the animal is firmly held till he subsequently breaks loose and floats 

 about in the fluid. The echinococci often die. The mother and 

 daughtei vesicles collapse, their contents become cloudy, fatty, and are 

 finally transformed into a smeary or putty-like substance. This con- 

 sists of chalky salts, fat, and cholesterin, and only a few of the hook- 

 lets of the echinococcus remain to betray t"ho origin of the mass. Sudd 

 compares these hooks to the bones and teeth remaining after the decay 

 of larger animals. 



In other cases the echinococcus sac gradually distends till it finally 



