1895.] Embryology. 1123 
In the elongated region from the twelfth to the twenty-sixth rings 
the distension of the intestine and the great protuberance caused by the 
large crowded lobes of the seminal vesicles are even more pronounced 
than in the other worm. 
The girdle is much contracted and constricted towards the ends in 
such a way that its thickened glandular wall extends both forward and 
backward beyond the constrictions into the neighboring regions. 
From such sections we learn that the girdle and the region opposite 
it and containing the seminal receptacles are much contracted while the 
long intermediate region between the girdle is correspondingly dis- 
tended. The ends of the girdle contractions are markedly constricted 
as deep annular grooves in which coagulated mucous serves as a cord 
to bind the two worms firmly together. The distended region is the 
one that contains the seminal vesicles full of sperm and the openings 
of their ducts on the fifth ring. 
In a series of transverse sections of the anterior portions of two con- 
jugating brandlings the condition of affairs at the contracted girdle 
region is especially striking. As shown in figure 5 oue worm more 
than half envelopes the other. The upper part of the figure is the 
girdle region with its thick glandular and thinner muscular parts of 
the body-wall on the dorsal and lateral sides but with a much attenu- 
ated body-wall on the ventral side, which is pushed in so that the 
lateral parts hang down and form a deep trough for the reception of 
the other worm. The other worm, below in the figure, is so much con- 
tracted that the muscular part of its body wall is very thick and it is 
moreover thrown into folds that farther increase its extreme diminu- 
tion in diameter. Its body cavity is very small and the digestive tract 
in it reduced to a minute tube as compared with the intestine in the 
other half of the section, in the girdle region of the other worm. In 
this shrivelled part of the worm enveloped by the girdle we see the 
ducts or outlets of two of the seminal receptacles, full of ripe sperm 
that stains deeply and is indicated in black. 
This section passes nearly between the ninth and tenth or tenth and 
eleventh rings of the worm enclosed below by the girdle of the worm 
above which is cut across about the twenty-eighth to thirtieth ring. 
The figure also indicates a cuticle like membrane passing from the 
girdle completely over the dorsal side of the other worm ; this is hard- 
ened mucous that lies close to the worms and binds them together. At 
the same time there is a smal] space left between the epidermis and this 
mucous cuticle and in this we find ripe sperm, especially, as indicated 
in the figure, in the angles where the surfaces of the two worms 
separate. 
