PARASITES OF ANIMALS. val 
* measles ” in pork (Figure 49). These are cavities or cysts 
produced by inflammation, containing whitish fluid and enclos- 
ing small, bladder-like, translucent, vesicles, filled with a watery 
fluid, and which contain the proper head and neck of the young 
worm coiled up spirally in the interior in an inverted position. 
By gentle pressure the head and neck may be made to protrude 
by inversion, like the finger of a glove, and will then present 
the appearance shown in figure 50, the vesicle of fluid now 
forming the flask-like caudal portion of the worm. The head 
may now be seen to have four suckers and a central promi- 
nence surrounded by two circles of hooks, as in the adult. In 
this condition, enclosed in the cysts, they will remain living 
Figure 53. Figure 54. 
| 
for a long time in the hog, even surviving the death of their 
host for a considerable period. Ifone or more of these young 
worms or measles be swallowed by a human being, the mus- 
cular fibres and the cysts will be digested, and each young 
worm thus liberated will evert its head, and losing its bladder- 
like portion, will pass into the intestine. There it will fasten 
itself to the inner membrane by its suckers and hooks, and 
grow rapidly by absorbing the digested food by which it is 
surrounded. New joints will be rapidly formed as the older 
ones grow larger, until it becomes a mature tape-worm, with 
joints ready to becast off. There may be but one tape-worm in 
Figure 53. Head of Tenia solium, magnified. From Cobbold. 
Figure 54.—A joint or proglottis of Tenia solium, magnified ; a, branches of the 
uterus ; b, external orifice ; Higitie@tyaiicrexon®Cobbold. 
