144 ENTOZOA FOUND IN MAN. 



they have acquired a large bulk, when the walls of 

 the cyst have become more or less cartilaginous or 

 osseous, when the cysts are multiple, and when 

 emaciation or inflammatory symptoms have followed 

 their appearance. 



They are commonly mortal if the general symp- 

 toms are persistent and become worse, after they have 

 opened into some organ which possesses an external 

 communication, if the matter which is expelled 

 assumes a gangrenous character, if pneumonia or 

 deep-seated suppuration supervene, or if the cyst has 

 discharged its contents into a large serous cavity. 



The pathological phenomena and the complica- 

 tions to which hydatids give rise, present, according 

 to the situations in which the entozoa exist, certain 

 points of difference which it is requisite to notice 

 before the various methods of treatment are indi- 

 cated. 



Chapter XIX. 



HYDATIDS WHICH AEE IN EELATION WITH THE 

 CIECULATOUT SYSTEM. 



Hydatids are sometimes observed in the blood- 

 vessels, either as a residt of their development there, 

 which is a very doubtful point, or else as a result of 

 their accidental communication with the vessels, 

 through the perforation of the walls of the latter, — 

 the vesicular worms having been primarily developed 



