XIX 



ON THE ANATOMY AND DEVELOPMENT OF 

 ECHINOCOCCUS VETERINORUM. 



Zoological Society s Proceedings^ vol. xx. 1852,//. 110-126 

 {PL XXVIII.-XXIX. [PI. 21, 22]). 



On the 25th of November, 1852, a fine female Zebra, whilst at play 

 within its paddock, accidentally broke its neck. The animal had 

 always appeared to be quite healthy, and it was in perfectly good 

 condition — but, upon examination, its liver was found to be one mass 

 of cysts, varying in size from a child's head downwards. The liver 

 was taken out of the body on the day succeeding the animal's death^ 

 — and on the 27th I proceeded to examine the contents of one of the 

 largest cysts (with a portion of its wall) and one of the smaller cysts. 



It was at once obvious that the cysts contained the Ecliinococciis 

 veterinorinn, and I may here mention that the EcJiinococci were in 

 full life, and remained so for three days, until, in fact, the fluid in 

 which they were contained had become slightly offensive. 



It will conduce to clearness, perhaps, if I state in successive order 

 I. What I saw myself. II. The theory of the formation of the 

 Echinococais-cysts, and of their relation to other forms of Entozoa, 

 which I have to offer. III. What has been done hitherto. 



I. The cysts are nearly spherical vesicles having a very elastic 

 proper wall ; so elastic, in fact, as to exercise a continual tension 

 upon the contained fluid, which, if the cyst be pierced, spurts out in 

 a jet for some time. 



The outermost layer of the cyst is an adventitious membrane, 

 formed by the infested animal around the Echinococcus-cyst, as it 

 would be developed round any other foreign body ; with this I have 

 nothing to do. Within this, and in nowise adherent to it, follows 

 the proper wall of the Echinococcus-cyst, which must be carefully 



I beg here to express my obligations to the Secretary of the Zoological Society, without 

 whose kind recollection of a wish to examine fresh Entozoa, which I had expressed, I should 

 not have had the opportunity of making the observations contained in the present paper. 



