610 STRUCTURE AND DEVELOPMENT OF THE ECHINOCOCCUS-HEADS. 



The formation and multiplication of these capsules takes place, 

 according to my observations (confirmed by Naunyn), as follows : 



At distinct points on the parenchyma one notices at first small, 

 wart-like elevations. These are proliferations of the cellular layer, 

 which are even already (according to Naunyn) possessed of a number 

 of actively vibrating cilia, which are still distinct at a later stage 

 even after the formation of the head. When the elevations have 

 grown to about double the thickness of the wall from which they 

 spring, one can recognise inside them a small spheroidal cavity, which 

 is very soon clad with a delicate cuticular membrane. Process and 

 cavity then grow to perhaps three or four times their original diameter. 

 The cellular layer, which had at first a considerable thickness, becomes 

 thin, and forms at some point or other, usually opposite the point of 

 insertion the first hollow bud which, sometimes as an external 

 appendage ((7), and sometimes inwardly invaginated (Z>), becomes the 

 first head, which is soon succeeded by others. 



Fio. 328. Development of brood-capsules (A) and of the appended 

 heads. (B\ first rudiment of the head ; (6'), further development j (Z>), 

 invagination ; (), subsequent budding. ( x 90. ) 



With the number of the budding heads the size of the brood- 

 capsule also increases proportionally, so that many attain a diameter 

 of 1*5 mm. Such large brood- capsules contain here and there per- 

 haps a dead head, which is separated from its germinal layer, and 

 is readily distinguished, by its shrivelled form and brownish colour, 

 from the living and active, though but slightly mobile, heads. 



It seems further as though the power of forming such brood- 

 capsules were usually confined to certain portions of the Echinococcus- 

 bladder, and never uniformly distributed over the whole inner surface. 

 This is what we find in the Cwnurus, where the heads are budded off 

 in groups here and there at varying distances apart. 



There is considerable diversity as to the size which an Echinococcus- 

 bladder must attain before it produces brood-capsules and heads. 

 Usually this process may begin when the bladder has become as large 



