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This hydatid is the larval form of the Zeta Lechinococcus, which infests the 
small intestines of the dog or wolf. The adult tape worm is composed of 
four segments or joints, and isa little over a quarter of an inch in length. 
The first joint includes the head, which is about one-hundreth part of an inch 
wide, and is provided with four suckers, a double coronet of hooklets, 
between thirty and forty in number, and a central beak. The fourth 
segment is as long as all the rest of the worm. The way in which the 
human being and the horse and other creatures become infested with this 
larval form is as follows :—-The mature worm in the intestines of the dog 
discharges its ripe eggs, and these being ingested by man or the horse, soon 
lose their shells, which are dissolved, thus liberating the six-hooked little 
embryoes. These bore their way into one of the blood vessels, and are thus 
carried to the various organs of the body, more especially the liver and lungs. 
When the embryoes have arrived here, they become metamorphosed into 
hydatids. The lining membrane of these little cysts then develops heads. 
The worm cannot undergo further development, unless the hydatid be 
eaten by some animal. 
Dr. Cobbold tells us that at least 1 per cent. of our dogs harbour the 
mature tape worm, and he asserts that in the United Kingdom several 
hundred human deaths occur annually from the ingestion of the eggs, which 
develop into hydatids. In some other countries, especially in Iceland, where 
dogs are so much used, and live in close contact with their masters, this 
disorder is fatally endemic, and thus Iceland stands at the head of the 
afflicted territories. Our Australian colonies are probably entitled to the 
next place of distinction in this respect (Cobbold). Dogs frequently convey 
the eggs of this parasite to man by licking his hands and face. Regarding 
the treatment of this larval form we have nothing to say, it being very 
rarely diagnosed in horses. Last year we had under treatment an aged cart 
horse suffering from chronic renal disease. The water passed contained 
abundance of matter. After death, thirty hydatid-cysts were found in the 
right kidney. They varied considerably in size, one being as large asa 
cocoa-nut ; the others varied from the size of a walnut to that of a pea. In 
the left kidney there were also more than a dozen of these cysts. 
