TAENIA ECHINOCOCCUS. ' 271 



their origin between the lamellae of the mother bladder, a fact, 

 however, which in agreement with Kuhl and Davaine, I have seen 

 more than once and have followed out step by step. The daughter 

 bladders (not speaking of the common sprouting) are said to arise 

 out of heads and brood-capsules which grow out gradually and 

 bladder-like beneath the thickening and lamination of their cuticle. 

 I have not the slightest doubt that the author has minutely watched 

 these processes, and I rejoice myself to be able to confirm one 

 method of this formation, namely, the bladder metamorphosis of the 

 scolices (which was not only previously asserted by Bremser, but also 

 by Yon Siebold and Wagener) . As the author has fally shown, 

 the metamorphosis commences in the hinder part of the body, 

 which, by the expansion of the inner cavity, swells into a bladder-like 

 vesicle, drawing gradually the front part with its crown of hooks into 

 it, and (by a thickening of the cuticle, as well as by the uniform dis- 

 tribution of the internal parenchyma) assuming more and more like- 

 ness to the echinococcus hydatid. Sometimes one sees develop- 

 ments which are only distinguished from the young echinococcus 

 vesicles by the adhering remnants of the former crown of hooks." 



I have purposely transcribed this passage in toto, because the 

 subject of the development of these echinococci is not only one of con- 

 siderable importance physiologically, but because there still remain 

 several disputed points which it is quite possible we may soon be 

 enabled to solve. Our best microscopic observers will here still 

 find abundant room for further research. Reasoning from analogy 

 as well as from personal observation, I am strongly of opinion that 

 Naumyn's views will turn out pretty correct. With Huxley I still 

 regard the endocyst as capable of forming solitary scolices. Some 

 of the scolices become differentiated to form brood-capsules, a por- 

 tion of whose individual echinococcus heads may, in their turn, be- 

 come secondary brood-capsules, whilst others fail to become either 

 scolices or secondary brood-capsules. It also accords more with 

 our knowledge of the general plan of development to believe that 

 the daughter and grand-daughter hydatids are likewise pecuharly 



