130 ENTOZOA FOUND IN MAN. 



ance may result from the fusion of several cysts. 

 When the hydatid pouch is multilocular, in conse- 

 quence of the obstacles which are opposed to its 

 uniform increase in size the hydatid, if it is entire, 

 sends prolongations into the various cells, as has been 

 pointed out by Cruveilhier. 



In Man, a cyst frequently encloses several 

 hydatids ; their number may be very considerable, 

 amounting sometimes to beyond a thousand. When 

 the hydatids are very numerous, the tumour always 

 attains to enormous dimensions. 



When the cyst only contains a single hydatid, the 

 latter usually completely fills it up, and lines its 

 walls ; when it contams several, some fluid in which 

 the hydatids float is found within its cavity. This 

 fluid is either transparent and limpid, like that which 

 exists in vesicles, or it may be variously coloured, 

 turbid, and thick. 



It has already been stated that hydatids have a 

 limited existence, and that they are sooner or later 

 destroyed, together with the echinococci which they 

 contain. This destruction is probably caused by the 

 action of the pouch which encloses them ; at any 

 rate, the entire mass of the tumour presents morbid 

 changes which do not appear to commence with the 

 hydatids themselves. 



When the vesicular worm is solitary, or when, 

 being multiple, these worms have their vesicle 

 attached to the cyst without the interposition of 

 fluid, a substance of a tubercular or fatty appearance, 

 and which is semi-liquid and viscid, or thick and firm, 

 is deposited in layers upon the internal surface of the 

 cyst ; this substance accumulates, and completely 



