8 TRICHINA SPTRALIS. 
and intestines like so many diminutive eels. They now increase in 
size, and another and far more important change takes place. The 
males and females become mature sexually, and unite to perpetuate 
their species. At this stage of their existence they present the 
appearance shown in Figures 4 and 5, Fig. 4 showing the male 
trichina and Fig. 5 the female. As in the case of other worms of 
Fig. 4. 
this class the small end is the head. In a few days the females give 
birth to living young, and shortly after that they die and are ex- 
pelled with the refuse food. Each female produces a number of 
young, which has been variously estimated at from two thousand to 
twenty thousand. lLeuckart, one of the very highest authorities, 
says not less than from ten to fifteen thousand. The young are 
born alive, and it is these embryos which cause the disease known 
as trichinosis or trichiniasis. 
As soon as they are bern, they proceed at once to bore through the 
walls of the intestines, and enter the muscles. Through the con- 
nective tissue of the muscles they mine their way, absorbing the 
juices of the flesh, and growing larger and larger, until their 
progress is arrested, either by their inability to bore through the 
tendons, or by the fact that they have reached their full size and it 
is time for them to curl up and go to rest. When this period 
arrives, the worm coils itself, as shown in Fig. 3, and a cyst or bag 
is formed around it. At first this cyst is perfectly transparent, but 
