Zoological Society. 383 



Professor Owen has stated (article Entosoa, Todd's Cyclopaedia, 

 1839) that the Echinococci (from the Pig) which he examined, 

 moved " freely by means of superficial vibratile cilia," p. 118. There 

 were certainly no such cilia upon the Echinococci of the Zebra. 



The movements of the Echinococci, so far as I witnessed them, 

 were confined to slow, undulatory, peristaltic contractions. I found 

 numbers in every stage of contraction, but I could not observe any 

 actually performing tbe process. The head with the hooks is drawn 

 in first, as one meets with many forms in which the suckers only 

 protrude at the extremity, like four knobs. The suckers then follow 

 and are turned completely in, so that their proper outer surfaces look 

 towards one another, the coronet of hooks lying beneath them. In 

 this state, which has been so often described, the animal has not 

 more than half its previous length, and takes on a great variety of 

 forms, oval, rounded, heart-shaped, &c. 



b. The secondary cysts. — When the fluid contained within one of 

 the large Echinococcus-cysts is emptied into a glass vessel, it is at first 

 turbid with minute white bodies, but these rapidly subside and form a 

 sediment at the bottom of the vessel. These white bodies vary 

 in size from -j-g-th of an inch in diameter downwards to y^-gth. They 

 are the secondary cysts. 



Under the microscope these bodies are seen to be delicate sphe- 

 roidal sacs, containing Echinococci. The largest examined had at least 

 thirty of these in its interior. It consisted of a very transparent 

 structureless membrane, apparently lined by a delicate granular film, 

 which was most distinct near the pedicles of the contained Echinococci. 

 These Echinococci in fact were not free like those contained in the pri- 

 mary cyst, which I have previously described, but each was attached 

 by a delicate cord, more or less resembling the "appendage" of the free 

 Echinococcus, to the inner wall of the secondary cyst, and radiated 

 thence inwards. These Echinococci resembled in all respects those pre- 

 viously described, except that I could observe no ciliary motion in them* ; 

 they were in all conditions of protraction or retraction, and exhibited 

 the ordinary movements. None were ever found free in a secondary 

 cyst, and the members of each cyst, as well as those in different cysts, 

 were as nearly as may be of the same size and degree of perfection. 



The space left between them in the interior of the secondary cysts 

 was sometimes filled with a clear fluid, and at others more or less 

 obscured by granules. In none of those observed by me was there 

 any trace of the peculiar mode of development of the contained Echi- 

 nococci from the granular contents of the secondary cysts described 

 by Von Siebold (vide infra). 



The membrane of these cysts was traversed by a meshwork of fine 

 clear delicate vessels, with distinct walls and about jjrWth to — ?— th 

 of an inch in diameter. These were not folds, as their lumen could be 



* This may well arise from my not having examined them till the 28th. 

 Lebert appears to have found the observation of the cilia to be favoured by the 

 interposed membrane of tbe secondary cyst (vide infra). 



