85 
‘They vary much in size, sometimes being as small as a pea, and occasionally 
as large as a good-sized cocoa-nut. They may or may not produce 
symptoms, which vary according to the organ invaded, and the size and 
exact position of the cyst. This hydatid is common in man, being often 
found in the liver, and sometimes in other organs ; and it may attain in him 
a very large size. This hydatid or cyst in its early form is small and 
globular, with transparent walls and finely granular contents. In its later 
stages, when it has much increased in size, the walls become thick, and the 
_ contents fluid. Sometimes these cysts contain several pints of clear fluid. 
In the above picture B shows the echinococcus of the dog, magnified ; 
€ is one of the little heads which are formed in the cyst wall ; X is the part 
where the head is attached to the cyst wall. 
