66 DISEASES OF SHEEP. 



wrinkled form, the head being provided with four suckers and 

 a double row of hooks. These animals are so connected with 

 the bladder that the latter appear to be the general body 

 of the former, and the animals themselves extending their 

 heads and necks upon the base of the bladder, and attach- 

 ing their sucking apparatus to the brain of the animal, by 

 which means the sap of the brain is absorbed to such-an ex- 

 tent that the brain of a dissected animal is often found to 

 be hardened yellow matter. When the bladder is situated 

 upon the surface of the skin, it is to be found under the 

 skull-bone and under the hard skin covering the brain ; the 

 growth of the bladder causes a pressure of the bone, by 

 which means the bone becomes softened and thinned, some- 

 times to such a degree that the bladder is only covered with 

 a skin, whereby the diseased spots may be easily detected. 

 Mostly, however, the bladder is found in the brain, and 

 seldom in other parts. Sometimes a large number of worm- 

 bladders may be found upon the same animal. In the be- 

 ginning of small size, the bladder increases considerably, 

 sometimes to the size of a hen's egg, and even larger. 

 There is no doubt that the worm-bladder is the immediate 

 cause of vertigo, as a consequence of the pressure of a 

 foreign body upon a most tender organ of the body. The 

 cause of the formation of the bladder is, however, still un- 

 known. One of the most celebrated and experienced prac- 

 titioners has published an essay containing very valuable 

 observations in regard to the formation and origin of said 

 disease, from which we give the following : 



In almost every case an inflammation of the brain pre- 

 cedes the formation of the worm-bladder and the disease of 

 vertigo, the strongest and healthiest lambs being mostly 

 -subject to the same. The animal is sullen, without appetite 

 and affected with constipation, the other symptoms being 

 the same as in regular inflammation of the brain ; there 



