FISH PARASITES COLLECTED AT WOODS HOLE. 287 



1. The process of egg-making in the liviny 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 tetrahcdral 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 ho 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 1 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 readies 

 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 bo 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 continued 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 ovulatiou narrated above. 



The duct which leads from the yolk reservoir passes dorsally (tig. 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 aud 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 

 feature, 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, and at a short distance from the point of union with the yolk 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 defereus in these sections is very 

 conspicuous and 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 and kindred forms would well repay careful study aud are commended to anyone who is 

 in search of a thesis for research work. 



