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the two forms are found in different individuals and different races 
of animals. Taking as our type the Twnia solium, we will trace 
its life developement. The egg, escaped from a segment which 
had already been expelled from its host, commences its own 
wanderings. Each embryo is furnished with a complete boring 
apparatus, consisting of three pairs of hooks situated at its anterior 
ends. By chance it is swallowed by a pig among the rubbish, 
and its outer shell crushed by the teeth. Thus set free in the 
stomach of the pig it begins a vigorous use of its spikelets, com- 
mencing to bore its way through the various organs, or perchance 
it penetrates a blood vessel, and is carried to the liver or the brain. 
The first portion of its path is traversed by bringing together the 
several pairs of spikelets so as to form a wedge-shaped stiletto. 
The lateral pairs are then brought back so as to thrust its body 
forward. In this free condition it is called a proscolex. Having 
arrived at some comfortable spot, say in the muscle, it settles 
down for a while into a more quiet life. Dropping its boring 
apparatus, it becomes enclosed in a vesicle or cyst, white, 
glistening, and filled with fluid. Gradually, during its abode, it 
developes a head, armed with four suckers and a row of hooklets. 
In this condition it is called a scolex, and is the larva of the tape- 
worm. A number of them together produce the appearance in 
pork, which goes by the name of the measles. In about ten weeks 
they attain the size of a pea to a kidney bean. Their further 
history consists in the pork being eaten without being properly 
cooked. The vesicles burst, the embryo, fixes its hooks and 
suckers in the intestine, and from it segment after segment 
grow, until a colony is produced, forming the mature ve@nia, 
it may be as much as 35 feet long. In about three months 
the lowermost segments contain ripe ova, and are discharged from 
the intestine. The head of the tcenia is barely larger than a pin’s 
head, armed with four suckers and a double row of hooks for 
anchorage. Each segment contains a male and female re- 
productive organ, and is entirely distmct from its neighbour. 
The only organ in common is the water vascular system. The 
lower segments coutain ripe ova. This metamorphosis of the 
tapeworm has four distinct stages—ovum and proscolex, both free ; 
scolex and perfect form, both fixed. It may, indeed, be compared 
in its developement to a butterfly— ovum, larva, pupa, and 
butterfly. It is only in the last 20 years that the connection 
between these cysts and the tapeworms have been worked 
out. Von Siebold and Leuckart fed dogs with the cysts from 
various animals, and invariably found they produced tenia, 
though difficult to say which tcenia. Not content with dogs, they 
determined to experiment on man. Thus Kuchenmeister fed a con- 
demned criminal, some hours before execution with some cysticerct 
from the hog. They disguised them as grains of rice in warm 
