28 
only three in which I found no tenia or ascarides. But these were 
all dogs that had led a city Arab life. Passing over the oxyuris 
and its allies, as closely resembling the ascaris, we must delay a 
while over the trivhina spirulis, for this little entozoon is invested 
with more practical interest, inasmuch as it has, perhaps, caused 
more mischief to the human race than any other. The mature 
trichina inhabits the intestines of man and animals. It measures 
one-eighteenth to the one-eighth of an inch in length, with a round 
file-form body, narrow head, finely pointed, unarmed with hooklets 
or suckers, and as a single oval aperture. According to Leuckart, 
on the second day after entering the intestine they attain their full 
size. In six days the female contains ova, the embryo freely 
moving in its shell, and when fully mature passes into the intestine. 
Thé embryo worm breaks its shell, and not content with the dull 
life of its parent, begins its wanderings. Boring through the walls 
of the intestines, it wanders freely through the muscles and tissues 
of its host, and if its host survives its invasion, it takes on the 
encysted form ; it curls itself up, becomes surrounded by a cyst, 
and here patiently awaits a further change. This change may 
never come, their bearers continuing to live in spite of them. 
They die, and a cretaceous deposit takes place around them ; or, 
on the contrary, their host is killed for food, the trichina cysts 
transferred to the devourer’s intestine, and once more their life’s. 
circle begins again. The presence of these free trichiaa in the 
muscles of their bearers is liable to give rise to a very serious 
inconvenience and danger to life. A single instance, related by 
Professor Langenbeck, of Berlin, will show this. Seven persons 
took part in a “ church visitation,’ which consisted in their sitting 
down to a heavy breaktast of ham, cheese, wine, and the eternal 
sausage. A few days after everyone of them were taken ill, and 
suspicion rested on the innkeeper for poisoning the wine. They 
had fever, pains in the muscles, &c. ; four of them died, and the 
other three were ill for some time afterwards. Some years after, 
one of the survivors had to undergo an operation which entailed 
excising a portion of muscle. This muscle was found filled with 
numerous dead trichina cysts. This evidence, with other circum- 
stances which-came to light, proved beyond doubt they had eaten 
pork in the sausage containing trichina cysts. Passing on to the 
Teeniada, or tapeworms, we meet anew elass of ontozoa. The 
mature teenia differ from the rematoid worms in their being des- 
titute of an alimentary canal, and consisting of a series of segments 
or proglottides, each of these being hermaphrodite. We meet with 
the tceniada in two forms, the sexually mature and the sexually imma- 
ture. The former inhabit those parts of their host that are in free 
communication with the exterior, in order that their ova may 
escape. The latter inhabit the solid organs of the body as in the 
liver. All parasites so found are immature, and generally speaking ~ 
