76 THE MICROSCOPICAL NEWS. 
a residence in the dog’s nose (Pentastoma tenioides), and another 
who takes up his abode in the walls of the heart (Filaria immitis ), 
while a third passes a part of his existence in the brain of the 
sheep, and at another stage in the dog’s bowels; others have 
existence in the connecting parts of the bowels of hares and 
rabbits, and develop a further stage in the dog that eats them, and 
so we shall find that man and animals keep up a continual round 
of reproduction, although some mature parasites require three or four 
hosts or intermediary bearers to complete their development. The 
Trichina, of which we have heard so much of late years, cannot 
find a home to its taste until it has bored its way outwards from 
the stomach and intestines, and lodged in the muscular: parts of 
the body. The fluke again, whose disastrous effect upon sheep 
is well known as the rot, seeks for its home the bile ducts of the 
liver ; while the horse worm, affecting calves, is most at home in 
the bronchial tubes. The Ss:roptera sanguinoleatea is a minute 
worm swimming about in the blood, and another kind of worm 
sets up a nest at the junctions of blood vessels. Another worm, 
34in. long, is happy nowhere but in the aqueous humour of the 
eye, while the largest strongle (.Strongulus gigas) is found coiled 
up in the kidney. It will be gathered from the foregoing remarks— 
and they are incontrovertible—that internal parasites have a very 
wide distribution, and the term worm fails to describe any but 
two or three of the best known varieties. In treating of worms in 
the dog we shall have to refer to their relations to man, since some 
of them are common to both, while others pass one stage of their 
existence in man and another in the dog. When the enormous 
power of reproduction is considered—one tapeworm segment 
alone bearing 30,000 eggs—it is not marvellous that so many dogs 
(and men too), suffer from worms, but rather a matter of surprise 
that any animal escapes the presence of such infelicitous guests. 
Of the round worms infesting the dog the Ascaris marginata 
s the most common. The males are from 2in. to 3in. in length, 
while the females attain to 4in. or 5in. From experiments made 
at Vienna it was ascertained that so large a proportion as 104 out 
of 144 dogs contained this species of lumbricoid; while experi- 
ments in England lead to the conclusion that at least 50 per cent. 
of dogs suffer from the same cause. These worms generally live in 
the small intestines, but are known to wander into the stomach, and 
give rise to inflammation of that viscus, and the other symptoms 
which we have already described as gastritis. They are occa- 
sionally passed out of the rectum either by the presence of some- 
thing obnoxious to them in the anterior part of the canal, or from 
a voluntary wandering which sometimes leads them so far out of 
their natural element as to be found in the throat and nostrils. 
Their presence in the intestine generally produces nausea, which is 
