78 ANIMAL PAEASITES. 



this previously absorbed fluid to pass mechanically through their 

 walls, and fall together, so that their sides come in contact over 

 larger or smaller spaces, and gradually in their whole extent. 

 If such a cyst be opened, we meet first of all with free fluid of 

 the nature described ; and on one of the walls of the cyst, or 

 most commonly at its base, with the collapsed and compressed 

 cystic worm. The scolices (whether one or more) of these cystic 

 worms are found to have extended their necks, heads, and jointed 

 bodies, whether deprived of their hooks or not. At the same 

 time, in accordance with the law^ to which inorganic fluids are 

 subjected, the fluid deposits a calcareous layer round the dead 

 cystic worm on its outer and inner walls, and this may easily be 

 broken off in large pieces. The cystic worm acts, in this case, 

 like a rough body, or a crystal which is laid in a mother-liquor, 

 and from which the crystallization or precipitation of the salt 

 proceeds. Chemical decomposition gradually extends further 

 and further in the contents of the cystic worm. The proteina- 

 ceous fluid is continually deprived of its aqueous constituents by 

 absorption on the part of the walls of the cyst, and a sort of 

 precipitate is formed of that well-known fatty, caseous, greasy 

 mass, which, being rich in calcareous matter, at first forms a 

 sort of lime-soap, but finally becomes converted into a complete 

 calcareous deposit, exactly such as we observe in the so-called 

 old apoplectic cysts in process of cure. During this process, 

 any of the hooks which may have still remained adherent to the 

 heads of the scolices, become completely detached, and at the 

 same time imbedded in the calcareous mass. In all the cases 

 above mentioned, with the exception of the last, the collapsed 

 cystic worm may be very easily displayed and recognised with a 

 little practice, even after it has been dead for years. This 

 process goes on somewhat differently in the Ecfiinococci. In 

 these, the true primary vesicle, originating from the six-hooked 

 embryo, never detaches itself from its enveloping cyst, so that 

 no accumulation of fluid takes place between the vesicle and 

 the enveloping cyst. Although a few purulent points between 

 the cyst and the worm appear to indicate that a similar 

 process may occur here as to a greater extent in the Cysticerci, 

 this, however, is never general. The contents of the Echinococcus 

 vesicle, after its death, consist of the same mass that we have 

 seen above to occur between the enveloping cyst and the outer 

 wall of the caudal vesicle of the compressed cystic worm. Now 



