13 



in the Ruminantia the cyst of the hydatid is always solitary in its ca- 

 vity, all the anfractuosities of which it accurately fills, and its shape 

 is consequently very irregular. Another difference exists in the cir- 

 cumstance that, in man and the Simiadce, the disease is usually con- 

 fined to a single locality, while in the Ruminantia, hydatids are 

 generally found disseminated in various viscera at the same time. 

 Both circumstances, perhaps, indicating a greater difficulty to the 

 dissemination of the seeds or eggs in the one case than in the other, 

 probably in consequence of some difference in the constitution of the 

 fibrinous layer which lines the containing cavity. In England, al- 

 most the first observation as to the connexion of hydatids and Echi- 

 nococci, is that by Mr. Rose, in 1833 (Medical Gazette), who appears 

 to think the connexion only occasional. They were afterwards treated 

 upon more fully by Mr. Curling, in 1837. 



In 1839, in the * Cyclopedia of Anatomy and Physiology,' Mr. 

 Owen repeats some of the errors of Laennec and others, and gives as 

 figures of the human Echinococcus the incorrect representations of Del- 

 leChiage, but he adds from his own observation, what does not appear 

 to have been seen by any other observer, viz., a description of the 

 mode in which the Echinococci swim about in the fluid of the cyst 

 by means of vibratile cilia. He also in another paper appears to 

 consider the hooklets of the retracted head of the animalcule as resem- 

 bling the teeth of the polygastric Infusoria, the stomachs of which, 

 also, he considers the transparent vesicles seen in the body of the Echi- 

 nococcus, to resemble, and the whole animalcule, he hints, should be 

 classed rather with \he poly gastric Infusoria than with the cystic Ento- 

 zoa. I will only remark upon this, that the cilia cannot be seen un- 

 der any circumstances in the dead state of the animal, and that the 

 true nature of the teeth or hooklets is too evident to allow of the above 

 supposition being entertained.* 



I will now briefly describe the Echinococcus and its containing 

 cyst. 



* In his lectures on the comparative anatomy of the Invertebrata, Mr. Owen re- 

 peats these observations, and then remarks on the absence of cilia in some dead Echi- 

 nococci from a deer. 



He also appears to consider them more as parasites of the Acephalocyst than as 

 having any more intimate relation with it. 



It is to be remarked that in those he himself observed, he did not notice any sucto- 

 rial disks. 



