VARIOUS FORMS OF TAPEWOKMS. 55 



leasing thousands of ova (a). These are taken ofl' the grass by 

 the lambs, or even two-year-old sheep ; sometimes even whole 

 segments may be devoured. Cattle, goats, antelopes, chamois, 

 gazelles, and the horse are also sometimes affected. The 

 embryos become released in the stomach of the sheep or other 

 animal. The six-hooked larva then commence to bore their 

 way through the walls of the ovine intestine, and finally 

 enter the blood, by which they are carried to various parts 

 of the body. Should any of these embryos reach the brain 

 or spinal cord, as very often happens, further development 

 takes place ; otherwise they apparently die a premature death. 

 After the larva has reached the cranium, it commences 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 larvse, shows red sanguineovis streaks on 

 its surface, very like the innumerable fine blood-vessels which 

 ramify over it, — these tracts have been formed by the mov- 

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

 then grows into the Bladder-worm, 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 were formerly known as Cosnurus 

 cerebralis (now as Multiceps multiceps), develops from three 

 hundred to four hundred scolices 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. These cysts are also found in the spinal cord. Spon- 

 taneous recovery may take place, but large numbers of sheep 

 are annually lost by this parasite ; and yet we do little or 



