462 
WORMS. 
EGG (a) AND SIX-HOOKED EMBRYO (6) OR 
Proscolex of tape-worm. 
numbers and minute size, some ultimately succeed in making their way in 
connection with either food or water into the stomach of an ox. Here the egg¬ 
shell is dissolved by the action of the digestive fluids, and a small embryo, the 
jDroscolex, is set free. This embryo is a small round creature furnished with six 
hooks, arranged in three pairs. Upon this proscolex the gastric and intestinal 
juices have no effect; but instead of undergoing further development in the 
alimentary canal of the ox, it bores by means of its hooks into the blood-vessels of 
its host, and is thus carried by the circulation into the muscles, liver, lungs, brain, 
or other suitable resting place, where it starts its growth. Here it elongates, 
and becomes larger, while the hooks drop off* and the central portion liquefies, so 
that a bladder of fluid is formed. When these bladders—which are oval and 
about a quarter of an inch in length—are found lying side by side between the 
muscular fibres of beef, the meat is spoken of as measly. The next step is the 
formation of the head, which takes place in the fol¬ 
lowing way. At one spot on the side of the bladder 
an infolding of the outer skin takes place, and this 
elongates until converted into a hollow sac project¬ 
ing into the cavity of the bladder. At four 
equidistant points near the bottom of the pushed-in 
sac the suckers of the head appear. The head 
therefore is developed outside-in, but subsequently 
it is pushed out, and the embryo, which in this stage 
is termed Cysticercus bovis, consists of a head, a neck, 
and a bladder. Beyond this stage the tape-worm cannot go so long as it remains 
in the body of the ox. If, however, the latter be killed for food, and its affected 
flesh eaten in an uncooked state, the bladder and neck of the Cysticercus are 
dissolved by the digestive fluids, while the head, which 
is often spoken of as the scolex, fixes itself to the walls 
of the intestine, its neck gradually elongates, and the 
body grows and becomes divided into segments, or 
‘proglottides. Another common tape-worm in Europe is 
T. solium, which is scarcely so long as T. saginata, and 
may be distinguished by the presence of a circlet of hooks 
on the head in front of the suckers, as well as by the 
smaller number of egg-sacs in the ripe segments. It has 
long been well established that human beings share with 
pigs in the breeding of this tape-worm, the bladder worm 
stage ( celluloses ) being found in one of these quadrupeds, 
and the cycle of development similar in all respects to 
that of T. saginata. In addition to being found in swine, 
the bladder-worm stage of T. solium also occurs in a few 
other animals, such as monkeys and dogs; and even in 
man, if through any accident an egg has been swallowed, 
the Cysticercus duly makes its appearance in the muscles, 
heart, brain, or eye, and may thus be the cause of very serious consequences. 
Another tape-worm (T. cucumerina), sometimes found in man, frequently lives in 
BLADDER-WORM STAGE (Cysti- 
cercus) of tape-worm. 
a, With head beginning to turn ; 
b, With head protruded. 
