PLATVHELMINTHAES Iol 
intestine of an ox. Here the egg shell is dissolved by the 
action of the digestive juices, and a small embryo, the proscolex, 
emerges (Fig. 66, G). The proscolex is a minute spherical 
embryo provided with three pairs of hooks, by the aid of which 
it burrows its way through the wall of the alimentary canal, 
and eventually passes into some blood-vessel, or into the body- 
cavity. If the former is the case, it is carried either to the 
liver, brain, lungs, muscles, connective tissue, or eye (Fig. 68). 
Its presence causes a cyst to be formed round it, pathological 
changes being induced in the surrounding tissues of the host. 
The embryo soon loses its hooks and begins to grow. 
Some of the cells in its interior liquefy, and a vesicle full of 
fluid results. These vesicles attain a length of 4 to 8 mm., and 
when found between the muscle fibres of beef or pork, the meat 
is technically termed measly. At one side of the vesicle the 
head commences to be formed; it arises inside out as a projec- 
tion into the lumen of the vesicle (Fig. 68). This projection 
is hollow, and on its walls, facing its own lumen, the suckers 
and rudimentary ring of hooks arise, whilst in the substance 
of its walls the excretory system is being formed. The head 
then turns inside out, and the result is a Cysticercus or bladder 
worm. The Cysticercus consists then of the head and short 
neck, termed the scolev, and of the bladder or vesicle. That 
formed by the embryos of TZaenia saginata is known as 
Cysticercus bovis, from the host it inhabits (Fig. 68). As 
long as it remains in the body of the ox, the Cysticercus is 
incapable of further developement ; if, however, it is swallowed 
by a man, the vesicle is digested, whilst the head fixes itself to 
the walls of the intestine, and commences to divide into pro- 
elottides. 
LirE-HistoRY OF TAENIA SAGINATA. 
NCOLERe seer eten: in man gives rise by strobilisation to the 
Proglottides......... these leave their host carrying with them the 
(ON ieoneenepanccnor which, when found on grass or in water, contain the 
Six-hooked S aenneee embryo or proscolex. This passes into alimentary canal of an 
ox, aud working its way into the tissues of this intermediate 
host, becomes the 
Cysticercus..........or bladder-worm. When this is eaten by man it develops 
into the 
Scolex. 
