18 



described ; and this central solid material appears to be very similar 

 to that of which the pedicles are composed. 



la specimens preserved in spirits, Echinococci of all imaginable 

 forms and appearance may be met with, — differences owing to decom- 

 position or mechanical injury; and in many cases no trace of them can 

 be found except the hooklets or spines, which, like the fossil remains 

 of animals, in Geology, remain as certain indications of their source, 

 and not unfrequently afford the only proof we can obtain of the true 

 nature of the hydatid. 



With regard to the mode of propagation of these animals, I have 

 nothing to advance further than to state, that I conceive the aggregate 

 adherent masses to be a stage probably in their development, and 

 that they proceed from a sort of gemmation, as described by Siebold 

 (Physiologie de Burdach). 



I will further remark in reference to this part of the subject, that 

 in almost all the aggregations of Echinococci, are to be seen, besides 

 the perfect Echinococci, one or more of a very different appearance, 

 and of various shapes, rounded, clavate or oval, also attached by a 

 pedicle to the central common mass, and usually rounded at the other 

 (figs. 2, 4, a, a, a), composed of a granular material, denser apparently, 

 and of a deeper colour, than that of which the bodies of the perfect ani- 

 mals are composed, and increasing in density or coarseness towards 

 the free extremity. Of their true nature, if they are not partially de- 

 veloped Echinococci, I am unable to speak. I do not consider the 

 transparent oviform bodies as ova. Some of them have a small cen- 

 tral spot or nucleus, and of their true nature I am also ignorant.* 



Much observation is yet required to determine the mode of the dis- 

 semination of the Echinococci in the bodies infested by them, as well 

 as in the matter of their own reproduction. Upon both which points 

 I had hoped to have been able to offer a few novel observations, 

 but am prevented by the great scarcity this autumn of hydatids 

 in the Ruminantia, probably in consequence of the long-continued 



* Since this paper was read, in examining some Echinococci obtained from the 

 liver of a man who died in Guy's Hospital, I observed a fact which may probably 

 throw some light upon the nature of these oviform bodies or spaces, and in some mea- 

 sure justify Mr. Owen's comparison of them with the stomachs of the polygastric In- 

 fusoria. In this instance the hydatid cysts were contained in cavities of the liver, and 

 bathed externally by a fluid deeply coloured with bile. The proper fluid, however, 

 of the cysts themselves, was limpid and colourless as usual, but many of the transpa- 

 rent oviform bodies of the vermiculi were of a bright yellow colour, which I suppose 

 to have been derived from the fluid external to the parent cyst. 



