444 THE MICROSCOPE. 



cross Hospital from rupture of the liver, occasioned by the 

 wheel of an omnibus passing over him. The simple cysts 

 containing these animals are always situated in cavities in 

 the interior. These cavities may be situated in any part 

 of the tissues or organs of the body ; they are more fre- 

 quently found in the solid viscera, and especially in diseased 

 livers. Fig. 217 represents the microscopical appearance 

 of the contents of a cyst. 



Mr. Busk, who has examined several of these cysts, 

 says-: " When a large hydatid cyst, for instance, in the 

 liver of the sheep, very shortly after the death of the 

 animal, is carefully opened by a very small puncture, so 

 as to prevent at first the too rapid exit of the fluid, and 

 consequent collapse of the sac, its internal surface will be 

 found covered with minute granulations resembling grains 

 of sand. These bodies are not equally distributed over the 

 cyst, but are more thickly situated in some parts than in 

 others. They are detached with the greatest facility and 

 on the slightest motion of the cyst, and are rarely found 

 adherent after a few days' delay. When detached, they 

 subside rapidly in the fluid, and consequently will then be 

 usually found collected in the lowest part of the cyst, and 

 frequently entangled in fragments of the inner thin mem- 

 brane. When some of these granulations are placed be- 

 tween glass under the microscope, and viewed with a power 

 of 250 diameters, upon pressure being employed it will 

 be seen, after rupture of the delicate enveloping membrane, 

 that the Echinococd composing the granulations are all 

 attached to a common central mass by short pedicles ; 

 which, as well as the central mass, appear to be composed 

 of a substance more coarsely granular by far than that of 

 which the laminae of the cyst are formed. This granular 

 matter is prolonged beyond the mass of Echinococd into a 

 short pedicle, common to the whole, and by which the 

 granulation is attached to the interior of the hydatid cyst, 

 as represented in fig. 216. In specimens preserved in 

 spirits, Echinococd of all imaginable forms and appear- 

 ances are to be met with, differences owing to decompo- 

 sition or to mechanical injury ; and in many cases no 

 traces of them can be found except the booklets or spines, 

 which, like the fossil remains of animals in geology, remain 



