150 Dr. Baird on Entozoa, or Intestinal Worms. 



up upon its hind legs ; the hinder quarters appear paralysed ; 

 the body exhales a bad odour ; tumours show themselves in the 

 belly; the extremities swell, and death at last ensues. The flesh 

 of pigs labouring under this disease becomes soft and insipid ; 

 the fat is white, and loses its consistence; it takes salt with dif- 

 ficulty, and soon spoils ; and it has been said that human beings, 

 after eating measled pork, are affected by sickness and diarrhoea. 

 As this kind of pork is prohibited being sold, of course the value 

 of a pig-keeper's stock becomes seriously injured. In France, 

 during the reign of Louis XIV., inspectors were appointed to 

 examine the tongues of all the pigs brought to market, in order 

 to detect any labouring under the disease, and prohibit it being 

 sold. The disease appears to be invariably fatal ; and the only 

 thing to be done is to kill the animal as soon as the slightest 

 symptoms make their appearance, and before the flesh of the 

 creature becomes tainted. 



Such are a few of the diseases and injuries produced in the 

 lower animals by the presence of Entozoa. Many of them, such 

 as those I have mentioned above, prove almost invariably fatal; 

 and it therefore becomes an object of great interest and vast 

 importance to the farmer and grazier to find out the means of 

 remedying these evils. It is with this object that I now en- 

 deavour to call the attention of the Members of the Berwickshire 

 Naturalists' Club to the history of these curious creatures. 



The researches of Steenstrup, which I have mentioned above, 

 prove that in the cases of two or three species, they can and do 

 enter the bodies of the animals in which they are parasitic from 

 without. Since these observations were made public, M. Siebold 

 of Berlin has published some extraordinary circumstances in the 

 history of these obscure animals, which, if borne out by subse- 

 quent observations, will open a new field for investigation. The 

 Cysticercus fasciolaris, for instance, an encysted Entozoon, which 

 inhabits the liver of the common mouse, he has found to be the 

 young of a Taenia which had become vesicular, and did not as 

 yet possess sexual organs. This encysted worm, when conveyed 

 into the stomach of the cat, becomes in a short time fully deve- 

 loped, and takes on the form of the Tcenia crassicollis, the tape- 

 worm of the domestic cat. The Cysticercus pisiformis, another 

 species of the same genus of encysted intestinal worms, which is 

 found in the peritoneum of the hare and rabbit, becomes, when 

 conveyed into the stomach of the dog, the Tania serrata, or 

 tape-worm of the dog. The changes which take place in this 

 latter species have been followed up by Siebold ; the Cysticercus, 

 while alive, having been conveyed by him into the stomachs of 

 young pups in milk, the animals killed at different periods of 



