144 
Sir Everard Home on the double organs of 
in the hole, which enables them to keep their hold of the 
ground ; and whenever they are disturbed, they pull them- 
selves asunder and retreat into their holes. In the act of 
copulation, as in the leech, the heads lie in opposite directions, 
so that the hooks of one worm attach themselves to the 
suckers of the other, which at that time swell out exceedingly, 
and form a cavity which is filled with mucus. The act of 
copulation is continued for a considerable time ; Mr. Bauer 
has watched them for several hours before they separated. 
The testicles andxwaria (in the breeding season) are shown 
in the annexed drawings to be very conspicuous in each 
individual worm ; and although no canal from the one to 
the other has been detected, there can be no doubt that, the 
semen of the testicles arrives at the ovaria by the coats giving 
way. The ova, after impregnation, are conveyed into cells, 
of which there are two rows on each side of the animal, and 
there deposited. 
It is in this situation the ova are hatched ; and the young 
are for some time nourished by a substance supplied from a 
corrugated canal shown in the drawing, which is met with in 
the intestine, but having no communication with its cavity ; 
this corrugated canal is firmly attached posteriorly to the 
parts behind the intestine, and sends off tubes to each of the 
cells in which the young are hatched : there is also an ex- 
ternal orifice leading into each of them. In these cells the 
young go into the crysalis state, and when the young worm 
is ready to leave the crysalis covering, which is of an oval 
form, pointed at each end, one or more of these pointed 
ends are thrust out at the external orifice, so as to appear 
