230 ANIMAL PARASITES. 



brief in treating of these creatures; and it is sufficient to re- 

 mark, that acephalocysts are six-hooked cestode embryos, the 

 growth of which lias proceeded without liinderance, but which 

 nevertheless have remained barren, or, more correctly, which have 

 never attained to proliferation and the production of scolices. If 

 such acephalocysts occur in places where normally developed 

 Echinococci usually take up their abode, we cannot call them 

 strayed cestoid embryos, but only embryo Cestoidea which have 

 been disturbed in their normal development and remained barren. 



For my part I regard as the characteristic marks of acepha- 

 locysts — 1. The presence of a vesicle adhering to the inner 

 walls of a larger cyst, from which it is capable of being detached, 

 or from which it is already detached in particular spots, but 

 never all over, and collapsed in wrinkles, and which presents very 

 sparing calcification in its white, scarcely discoloured walls them- 

 selves. 2. The transverse section exhibits walls consisting of 

 very distinctly developed, parallel, concentric layers. 3. The 

 Avails have a peculiar, gelatinous, elastic trembling. 4. The 

 contents consist of a watery fluid, or of a substance which has a 

 purulent consistence, and contains the microscopic elements of cl- 

 cifying encysted proteiue masses in the act of resorption. Lastly, 

 the vesicle sometimes conceals, in its interior, secondary cysts 

 with gelatinous walls, in which, however, we seek in vain for 

 scolices of Cestodea or their remains, especially their hooks. 

 The acephalocysts which are referred to here belong to the fol- 

 lowing three species of Tcenice ; 



1. Acephalocysts derived from Tcenia Echinococcus scolici- 

 pariens. — Many of those acephalocysts which bear no daughter- 

 vesicles in their interior must be referred to this species. 



2. Acephalocysts derived from Tcenia Echin. alt rici pariens. 

 — These are acephalocysts with a formation of daughter-vesicles. 

 With regard to these, however, I would observe that many 

 examples may probably have slipped in as acephalocysts, which 

 in reality were true Echinococci, in which, from the want of 

 good instruments, or of practice in investigation, or from other 

 causes, the scolices could not be detected. The symptoms, 

 progress, prognosis, etiology, and treatment are the same as 

 with the Echinococci. The only remarkable thing, perhaps, 

 is the circumstance that the enveloping cysts of acephalocysts 

 with clear, watery contents, and of a small size, are thicker 

 and more cartilaginous than those of the true proliferant 



