186 PARASITOLOGY. 



branes; the hydatic membrane is thick while the 

 germinal membrane is thin. The cyst develops 

 very slowly and arrives at this stage in about five 

 months ; on the inner surface of the mother mem- 

 brane appears a minute papillary elevation which 

 becomes hollowed in the center and forms another 

 cyst called the daughter cyst (secondary or proliger- 

 ous cyst) . This is attached to the mother membrane 

 by a short pedicle ; the bud from the mother mem- 

 brane may develop a larva or scolex which is attach- 

 ed to it by a short slender pedicle ; this development 

 may proceed until fifteen or twenty heads are there 

 attached ; on the inner side of the daughter vesicle 

 may be developed five to ten heads or larvae or 

 another vesicle called a grand=daughter vesicle ; the 

 grand-daughter vesicle may develop within it another 

 cyst called a great=grand=daughter vesicle, which is 

 always an acephalocyst. These secondary cysts 

 may develop so as to be practically outside of the 

 mother cyst, thus, multiple cysts result. The cyst 

 contains a colorless poisonous fluid of saline, neutral 

 or slightly acid reaction ; this development goes on 

 until the entire organ is filled with multiple cysts ; 

 these cysts vary in size up to one and one-half 

 inches in diameter. This conditron is called echino- 

 coccus veterinorum, echinococcus polymorphus, 

 echinococcus granulosus or cysticercus echinococcus. 

 Sometimes instead of this form of cyst formation there 

 is formed a cluster of cysts varying in size from a mil- 

 let seed to a pea; these are in clusters like a bunch of 

 grapes and are called echinococcus multiloculaiis or 

 echinococcus alveolaris. These cysts may undergo 

 degeneration ; the cyst wall ruptures and the cyst 



