1024 The American Naturalist. [November, 
the length of a ring, every other ring will have a drop of sperm in its 
furrow at any given moment. The sperm thus flows from the 15th ring 
to the girdle outside the animals, covered only by a layer of mucous 
We may calculate the time taken as about 80’”. ; 
The girdle now becomes especially active. Its muscular elevations 
on the sides and at each end contract rhythmically about fifty-five times 
a minute to form shallow depressions which advance in a wave-like 
manner. The lateral depressions move downward and the end depres- 
sions toward the middle of the girdle ridge so that the sperm that has 
been poured out and accumulated between the worms under the girdle 
is concentrated, more and more, about the openings of the seminal recep- 
tacles, which lie opposite to the swollen part of the girdle. The same 
object is accomplished also by a second rhythmic motion that occurs 
about twice a minute; the lateral part of the girdle alternately presses 
against and lifts up from the other animal and so drives the sperm to- 
wards the openings of the seminal receptacles. There is no doubt that 
the sperm is taken into the seminal receptacles; their openings lie free 
under the mucous envelope and the sperm may be seen collecting about 
them. Perhaps the taking in is brought about by some sucking action 
of the receptacles. Though the ridge on the girdle continues to collect 
the sperm about the openings it cannot press it in as it does not cover | 
them. G. Meissner mentioned accessory organs concerned in introduc- 
ing sperm and eggs into these narrow openings, but as yet I have found 
‘none. : ; 
When the ejection of sperm is finished the longitudinal swelling and 
furrow slowly disappear in the direction opposite to that in which they 
appeared. The contractions of the girdle yet continue for some time 
till the sperm has so far disappeared that only a small drop remains 
about each opening of the seminal receptacles. When the conjugation 
has taken a normal course these white drops are found on both worms 
and on both sides of each. I often examined them microscopically and 
never found any eggs though they probably would have been present 
_ if, as Meissner supposed, they are taken into the receptacles along with _ 
_ the sperm. ee at oe ee | 
_ At length the worms separate from one another b rful wrench 
_ for which the tail ends that still remain in the ground serve as points — 
Of resistance. If we cut off both tails at once the worms often remain 
_ united for hours. If thrown into spirit they die without separating. 
~ The entire act of conjugation lasts two to three hours and may be 
_ easily observed under the lens since the worms are shy only in the early _ 
~ Stages while when an intimate union has taken place we may use a 
-brilliant light and even lightly touch without disturbing them. 
