VARIOUS FORMS OF TAPEWORMS. 49 



mences to burrow about until it finds a suitable resting-place 

 for further growth. A brain examined fresh when it has been 

 invaded by one or more of these larvae shows red sanguineous 

 streaks on its surface, very like the innumerable tine blood-vessels 

 which ramify over it, these tracts have been formed by the 

 moving embryo worms. On taking up its fixed abode, the larva 

 now grows into the Bladder -teorm, the so-called hydatid, or 

 "water-bag" of the shepherds, which gradually swells until it 

 reaches the size of a walnut, or even larger. The writer has 

 twice taken these cysts from lambs nearly as large as an egg, 

 the hosts, needless to say, having died. Often several cysts are 

 found in the brain, both on its dorsal and ventral moieties. 

 Each of the cysts, which are known as Ccenwnis cerebrcdis, 

 develops from three hundred to four hundred scoUces by asexual 

 budding. These can easily be seen in the " hydatid " as minute 

 white specks. The affected sheep gradually lose their power of 

 equilibrium, turn round and round, and fall down. In the 

 early stages of infestation the lambs shake their heads and hold 

 them on one side ; but as the " bladder " grows the symptoms 

 become more marked. Spontaneous recovery often takes place, 

 but large numbers of sheep are annually lost by this parasite ; 

 and yet we do little or nothing to prevent it, when prevention 

 lies easily in our power. 



Should a human being eat the diseased brain, cyst and all, no 

 further development would take place, but he does not do so. 

 What generally happens? The head of the "pothery" or 

 "sturdy" sheep is invariably given to the shepherd's dog. 

 What is the result 1 The cyst, being only capable of develop- 

 ment in one. of the Canidm, produces hundreds of the tapeworm, 

 Taenia caenurus, in the dog's intestines, and so the disease is pro- 

 pagated ; whilst if the diseased heads were destroyed or given 

 to fowls, in which the scolices, I find, never develop, all that per- 

 sistent loss to one of our most paying branches of stock would 

 be saved. The cysts are often found in the lumbar region of 

 the spinal cord, where they may reach a great size, and produce 



