ARTICULATA. 



273 



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 col- 

 lected in the lowest part of the cyst, and frequently entangled in frag- 

 ments of its innermost thin membrane. When some of these granu- 



fig. 117. The Guinea-worm, taken from the leg of a Negro. 



1. Represents the form of the worm when first taken from one of the sacs seen at fig. 2. 

 3. The young worm rolled up. 4. The worm extended. 



lations are placed between 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 

 Echinococci composing the granulations are all attached to a common 

 central mass by short pedicles ; which, as well as the central mass, ap- 

 pear 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 Echinococci into a short pedicle, com- 

 mon to the whole, and by which the granulation is attached to the in- 

 terior of the hydatid cyst, as represented in fig. 118. 



In specimens preserved in spirits, Echinococci of all imaginable 



T 



