1895.] Embryology. 1023 
each hollows out the girdle and the neighboring rings into a boat- 
shaped depression. The other worm lies in this excavation. There is 
then a copious secretion of mucous that gradually hardens on the sur- 
face and encloses both worms is a common envelope. The union be- 
comes closer and closer, especially so in the regions of the girdle and of 
the male openings. 
The ventral elevations of the girdle always lie opposite to the 9th, 
10th and 11th rings of the other worm while the ventral elevations 
about the male openings lie opposite to the 26th ring. 
The elevations of the girdle begin to contract rhythmically. Ante- 
rior to the girdle the region between the upper and lower setæ on each 
side swells up as a longitudinal elevation bounded by two longitudinal 
grooves. As the worms lie on one side this can be seen only on the 
other, upturned side. This elevation forms gradually from behind for- 
ward as far as the 15th ring when it terminates in the glandular swell- 
ing about the male opening. Ina live worm the position of the grooves 
bounding the above elevation is indicated by two more or less darkly 
pigmented parallel lines on each side from the 15th ring to the girdle 
(Hoffmeister erroneously regarded these as canals). When a worm is 
thrown into spirit it generally forms in its violent contractions both 
the longitudinal elevations and the boat-like excavation of the girdle. 
Since the ventral surface is flattened out or even made concave dur- 
ing conjugation the ridges of both worms lie pretty close together and 
the lower or less essential furrow is concealed from observation. The 
upper furrow, however, is evident as a longitudinal groove along which 
we may see waves of muscular contraction passing from before back- 
ward. This contraction consists essentially in a change in the furrow 
and its rims. The rims draw together to form a pit in the 15th ring 
which then passes back to the girdle, like the trough of a wave. In 
one minute about fourteen such pits may be seen to form and pass 
back. 
The ejection of sperm takes place only after an hour or more from 
the beginning of conjugation. We see a small drop ooze out of theslit 
in the elevation of the 15th ring and enter the longitudinal furrow 
where it looks like a white rod about as long as a ring is wide. This 
drop of sperm is taken up by the pit above described and led back- 
ward, Whenit has proceeded abouts its own length from the opening 
a new drop is poured out and so on. The ejection of sperm thus takes 
place with rhythmic interruptions and we see passing back in the furrow 
a row of small white rods separated by intervals equal to their own 
length. As the rods as well as the intervals between them just equal 
