STRUCTURE AND DEVELOPMENT OF ECHINOCOCCUS 253 



tains, in addition, calcareous corpuscles, muscular fibres and excretory 

 vessels. 



The development in cattle often remains stationary at this 

 stage, and they are then called " acephalocysts " or echinococcus 

 cysticus sterilis. In other cases large numbers of small, hollow " brood 

 capsules " are formed within the internal space, but are not arranged 

 in any particular order. The order of the layers is just the reverse 

 in them to what it is in the parent cyst, that is to say, they are 

 clad inside by a thin cuticle and carry the parenchymatous layer 

 on their external surface. Scolices (fig. 176) form, internallv or 





FIG. 178. A piece of the wall of an Echinococcus veterinorum stretched out 

 and seen from the internal surface. 50/1. A few brood capsules with scolices directed 

 towards the interior and exterior. 



externally, their number being variable (three to twenty or even 

 more). 1 This form occurs chiefly in domesticated animals and is 

 termed Echinococcus veterinorum, Rnd., or Echinococcus cysticus 

 fcrtilis. 



In man, and only rarely in cattle, the mother cyst first forms 

 '' daughter cysts " (Echinococcus hominis, Rud., fig. 179), which, 

 though smaller than the " mother cyst," resemble it in the struc- 

 ture of their walls ; thus they are covered externally by a stratified 



' Goldschmidt, R., " Z. Entw. d. Echinococcuskopfchen " (Zool. Jahrb. Anat., 

 1900, part xiii., p. 467). 



