FISH PARASITES COLLECTED AT WOODS HOLE. 
287 
1. The process of egg-making in the living worm. — One of the lobes of the yolk reservoir appears 
to empty itself suddenly by a short duct into the common duct immediately in front of the ovary. 
Thence the mass of coarse granular yolk is seen to pass rapidly forward along the duct to the capsule 
mold, where it is shaped into a tetrahedral form by the muscular walls of the mold. As soon as 
the mass of yolk reaches the mold the passage closes just behind the mold, where a comparatively 
solid base is formed, against which the mass of yolk is hammered into shape by the walls of the 
mold. At the same time the capsule is built around the mass of yolk. The material of which the 
capsule is formed appears to be secreted by what was interpreted to be the shell gland, which was 
situated about midway between the mold and the ovary. 
It was not clearly evident where the slender filament was formed, although I thought I saw it 
lying in the spiral common duct, between the shell gland and the mold, just before the discharge of 
an egg. When the capsule is nearly finished a very small fine granular mass makes its appearance sud- 
denly in the common duct at about the level of the shell gland. This mass, apparently injected into 
the common duct from the dorsal side, travels rapidly along the common duct, and as soon as it reaches 
the mold the completed egg is ejected forcibly by powerful contractions of the muscular walls 
of the mold. The duct through which it passes lies between the cirrus and the seminal receptacle. 
When an egg is not in transit this uterine duct is difficult to see, the walls being apparently nearly 
approximate. 
The rush of yolk from the yolk receptacle to the common duct probably creates sufficient suction 
to draw a germ cell from the short communicating duct. Germs were distinctly seen in this duct and 
they were also seen to be set into oscillatory vibration when a mass of yolk was passing, but the yolk 
mass itself concealed the proximal end of the communicating duct, so that no germ cell was actually 
seen to leave the duct to join the yolk mass, although when the latter reached the egg mold, a germ 
cell could occasionally be seen among the coarse yolk granules. The fine granular mass which joined 
the egg just before it was ejected was inferred to come from the seminal duct. This inference is appar- 
ently confirmed by structures revealed in serial sections as described below. 
Egg-making would proceed actively for some time, 10 minutes or more, then would follow a short 
period of rest. Unfortunately the time occupied in making an egg was not noted until the specimen 
had been under observation for 2 or 3 hours and had presumably lost much of its vitality. When 
noted the period occupied from the time when a mass of yolk left the reservoir until it was ejected as 
a completed capsule was about 40 seconds. 
2. Confirmation of some of the above-mentioned inferences. — Sections, both transverse and horizontal, 
were made of this interesting worm. The results were highly satisfactory, but the anatomical details 
are so numerous as to be altogether out of place in this report. I shall mention only certain details 
of structure which explain some of the phenomena of ovulation narrated above. 
The duct which leads from the yolk reservoir passes dorsally (fig. 14, yd), hence can not be seen 
plainly, either in dorsal or ventral view, in the living specimen. The duct from the germ gland also 
has its outlet dorsally, and the two connect in such a manner that when a mass of yolk rushes 
along the yolk duct and into the common duct, a suction would be created which would tend to draw a 
germ from the germ duct. While the germ duct is spacious at its beginning in the germ gland, which 
featnre, indeed, could be seen plainly in the living specimen, where numerous ripe germs could be seen 
oscillating every time a charge of yolk passed toward the shell mold, the duct grows narrower 
distally, aud at a short distance from the point of union with theyolk duct is but little wider than the 
diameter of a single germ. Since the amount of yolk which is necessary for a single egg is doubtless 
regulated by reflex nervous action, the whole apparatus has become adjusted with wonderful nicety, the 
several parts to each other, so that, when normal conditions prevail, just enough suction is created 
by the charge of yolk to draw a single waiting germ cell from the germ duct. 
Another fact demonstrated by serial sections is that at a point but a short distance from the 
junction of germ duct with yolk duct, the common duct is joined by a small duct which was traced 
to the seminal receptacle. The latter is a thick-walled, muscular organ, lined with what in the 
sections look like cilia. It lies to the left of the other reproductive organs and has its external aperture, 
like them, at a notch on the left side of the head. The seminal duct is very much smaller than the 
vas deferens and does not stain so deeply with carmine. The vas deferens in these sections is very 
conspicuous aud can be traced with ease from the testes forward in a somewhat tortuous course to 
the seminal vesicle at the base of the cirrus pouch. 
This aud kindred forms would well repay careful study and are commended to anyone who is 
in search of a thesis for research work. 
