SOCIETY MEETINGS. 
141 
cision just made. One distinctive characteristic of this mem¬ 
brane is a very persistent tendency of the cut edges to roll up. 
In fact it is almost impossible to make it lie spread out upon a 
plain surface or on the palm of your hand. This powerful ten¬ 
dency to roll up is not possessed by any other membrane, ac¬ 
cording to some writers ; hence when we find such a membrane, 
even when lacking particular characters soon to be mentioned, 
we may be reasonably certain the structure under observation is 
the mother membrane of an echinococcus cyst. 
A close inspection of the inner surface of this mother mem¬ 
brane shows it to be studded over by a great number of very 
small greyish white bodies or granules which are loosely ad¬ 
herent and may be easily scraped away. I have mounted a 
number of these minute bodies on a microscopic slide and if you 
will examine them under a lens magnifying 75 to 100 diameters 
you will readily see that these little bodies (proliferous cysts) 
contain from 15 to 30 pediculated tapeworm heads. Each head 
is provided with two oval disks, called sucker disks and a ros- 
tellum of hooks. They constitute the fixation apparatus of the 
future worm. In nearly all the heads these organs are invagi- 
nated. 
In these drawings pinned on the wall you have a magnified 
picture of a typical hydatid, and a representation of the more 
common modifications, such as the daughter and granddaughter 
cysts which develop from the mother membrane and may pro¬ 
duce the little granular bodies containing the tapeworm heads. 
Sometimes many small cysts are found, but in which the 
minute tapeworm heads cannot be found. These are known as 
acephalo cysts. 
This last drawing represents the adult worm as found in the 
intestines of the dog. The mature worm varies from one-sixth 
to one-fifth of an inch in length and is composed of only three 
or four segments, the last one of which is nearly as long as the 
first three, is sexually mature and contains several thousand 
eggs. It is readily understood that a dog which eats two or 
three cysts such as we have just examined, would become in¬ 
fested with a large number of these parasites. The heads attach 
themselves to the walls of the small intestines and become ma¬ 
ture within 60 days, thereafter releasing the last or fourth seg¬ 
ment as soon as ripe (ovulation completed) and continuously 
developing others. In this manner myriads of eggs are pro¬ 
duced and pass out with the faecal discharges. The segments 
become dried, powdered and the fragments are blown about by 
