1895.] Embryology. 1025 
The formation of the grooves and the ejection of sperm do not always 
take place simultaneously in both worms. They may also be of consider- 
ably different dimensions and yet accomplish conjugation since they are 
so changable in form. As a rule, however, both worms act in every 
respect alike. 
As it seems scarcely credible that the sperm should not spread out 
on the moist surface of the body one might at first suppose that it flowed 
back in a canal covered only by the transparent epidermis, yet no such 
canal is to be found nor any opening at the girdle. Moreover the 
seminal ducts open directly to the exterior and in handling a long 
worm, I once saw issue a white drop of what proved under the 
microscope to be sperm. 
After conjugation a small flat, club-shaped process is found on each 
side of the worms. This so-called penis is about 1’” long and is gener- 
ally in the region of the 26th ring, seldom at the girdle. It generally 
lies in the region of the ventral sete, sometimes on and sometimes 
between rings. It is sometimes duplicated and sometimes absent upon 
one or both sides. It gradually becomes harder though at first soft; 
it is a hyaline mass with a droplet of sperm imbedded in its free end. 
In my opinion it is made of hardened mucous. Before conjugation it 
is absent; if we separate conjugating worms before ejaculation it is soft 
and contains no sperm; it is demonstrably a product of conjugation. 
When formed in the region of the 26th ring opposite the male opening 
it receives sperm from the other individual and in the few cases in 
which it is on the girdle it receives sperm from the worm on which it is 
found. In the miele cases in which it lies on other regions of the 
body it contains no sper 
It seems superfluous to i ddacelie all the varieties of form, number and 
position of such an unessential structure.” 
Many features of the above remarkable interchange of sperm may 
be readily observed in wet nights in the Spring and Autumn in the 
public parks of Baltimore where this large earthworm, Lumbricus 
terrestris has been introduced. 
In the case of the smaller brandling, direct observation is precluded 
by the fact that the worms do not come to the surface to conjugate but 
lie closely appressed and bent some inches beneath the surface of the 
wet dung heaps they abound in. When disturbed they slowly separ- 
ate. The following facts relative to their conjugation are hence con- 
fined to observations upon preserved material. 
At Byrn Mawr, Penn. in May, 1892 and in Baltimore in May, 1895 
attempts were made to harden the worm in pairs by the use of Perenyi’s 
70 
