OXYUEIS VERMICTJLARIS. 371 



longest, runs straight backwards, often a short distance beyond 

 the anus, whilst its anterior and shorter branch runs, also straight, 

 as far as the region in front of the bulb of the oesophagus, always 

 supposing that the uteri are full. The branch which runs back- 

 wards, and at the same time gradually diminishes, covers the 

 entire intestine, and lies upon it, so that only the spot where 

 the anus is situated remains free; if it be empty, the dark 

 intestine shines through it distinctly. In the neighbourhood of 

 the anus the uterus bends round towards the other side and 

 runs forwards in the form of a considerably diminished finally 

 linear chord, filled with granular yelk-masses, terminating in 

 narrow convolutions behind the vagina. The branch which 

 passes forward runs not so much upon, as close to, and on the 

 inside of, the intestine, stomach, and oesophagus, pressing these 

 organs more towards the outer wall of the worm. It also 

 bends round at last quite anteriorly towards the other side, 

 passes consequently to the outer side of the intestinal canal, 

 and then runs backwards beneath it to just in front of the 

 vagina as an ovary, terminating here in five convolutions, like 

 the other branch. It is difficult to see this in mature indivi- 

 duals, and I could not succeed in it, until at last I hit upon 

 the idea of taking these worms out of my own faeces, with which 

 one or two Oxyurides pass off daily. These I laid immediately 

 upon a glass, covered it with a glass cover, and added some of 

 my saliva. In about three hours the animals had deposited all 

 their eggs, with peristaltic movements of the uterus, which expelled 

 the eggs, 5 — 12 at a time, by jerks, at intervals of about 5 — 10 

 seconds. At the same time the margins of the uterus became 

 crumpled, and the uterus appeared quite empty and without 

 epithelium. These movements of the uterus lasted for some 

 hours after the last eggs were laid. Professor Von Wittig, of 

 Konigsberg, who happened to be visiting me, was able to observe 

 this oviposition with me. Pressure sometimes causes the 

 vagina to open again when it has closed. The eggs, the form 

 and size of which we have already described, are present in 

 immense numbers, and are formed in the same way as the ova of 

 other Nematoida, and contain the most various steps of develop- 

 ment, from the segmentation of the yelk up to the filiform 

 coiled up embryo within the egg-shell. The eggs which pass 

 last out of the vagina have a small light point at one pole, 

 probably the remains of their attachment and of their place of 



