CESTODA. 829 



were wanting in that particular spot. Into this softened spot a 

 trocar and cannula are introduced, and after the trocar is with- 

 drawn — leaving in the cannula — a syringe is applied to the latter, 

 and the bladder extracted. 



" The prevention of the hydatid disease," says a writer in the 

 Agricultural Gazette, " must begin at its source, and the first step 

 is to expel the tape-worm from the intestines of the dog or dogs 

 which are employed in the farm. It may be objected that this 

 measure will be applied too late to remedy the mischief if the 

 existence of the tape-worm is not suspected until some of the 

 flock become affected with " gid ;" but in fact the existence of 

 tape-worm should always be suspected, and dogs should be 

 treated periodically with areca nut as a measure of precaution. 

 A dose of half a drachm to two drachms of the grated nut may 

 be given now and then with safety, even when the tape-worm 

 segments are observed, and if the remedy is not followed by the 

 expulsion of a worm, the animal may be deemed secure. A 

 second important means of prevention is to prevent the infection 

 of dogs by destroying bladder worms immediately on their re- 

 moval, instead of throwing them either to the dogs or in places 

 where the animals can easily discover them. If this plan were 

 universally adopted cystic entozoa would soon be diminished in 

 number, and one source of loss to the stock-owner be averted. 

 Sheep suffer from the entrance of embryos, which are expelled 

 from the intestines of the dogs. Dogs become infested with the 

 tape-worm in consequence of introduction into their digestive 

 organs of the larval forms of the parasites, which exist in the 

 brain of the sheep, being given to them, or placed within their 

 reach. This interchange can be prevented by the exercise of 

 a little common care. 



" Sheep which are pastured on common lands, or fields through 

 which a right of way exists, are exposed to risks of various kinds 

 from which animals in isolated positions are exempt, and under 

 such circumstances it is impossible to apply any effectual 

 measures of prevention. In the case of " gid " some amount of 

 danger is incurred from wild animals ; foxes, for instance, may 

 harbour the Tmnia ccenuriis, and a few sheep may here and there 

 become infested with bladder worms from eating the eggs ex- 

 pelled from the intestines of those animals, but these causes of 

 infection are occasional and remote, and do not materially affect 



