316 MR. H. H. STIRRUP ON 



Ovaries and Oviducts. — Tlie ovaries are situated in segment 12. 

 In the mature worm the ova are so large that they almost fill 

 np the whole of the bocly-cavity in that region, and are of a 

 pure white colour. When ripe, they break away from the ovary 

 and lie apparently quite freely in the body-cavity. 



In the lower Oligochastes there are no special ducts for the ova, 

 e. g. u^olosoma simply has a median pore. Beddard (1) says that 

 " the structure of the oviducts in Enchytrteids is such as to 

 suggest a degenerate condition." D'Udekem's opinion was that 

 the sperm-ducts served as ducts for the ova also. Later it wa,s 

 suggested that there might simply be pores in the body-wall 

 through which the ova might escape to the exterior. For some 

 time these pores could not be found, but Claparede (4) at last 

 described a pair of pores behind the male pores in Enchytrceus 

 vermicidaris, and these were afterwards verified by Vejdovsky 

 and Michaelsen. However, both Yejdovsky and Michaelsen 

 regarded them as mere pores for the escape of the ova without 

 a.ny trace of oviducts. Beddard (2) has described the oviducts in 

 PachydriliLS (Euchytrseidse). They consist of a few pear-shaped 

 cells, not ciliated, which fringe the orifices. He regards them as 

 degenerate oviducts. 



My own observations on E. pellucidus show that there is 

 certainly a pair of these pores in the body-wall in segment 13. 

 But, instead of a few non-ciliated cells fringing these openings, 

 it is quite plain that these two pores communicate with a single, 

 large, thin-walled sac, which fills up almost the whole of the body- 

 cavity in this region. Since the mature ova in this Enchytrseid 

 a.re large, then either the ova are capable of altering their shape 

 with ease or else these pores are capable of great distension. The 

 former seems to be most likely, as there are no extra muscles 

 connected with these female pores. 



ApPEJfDIX. 



Astomatous Ciliate Protozoa in the Gut. 



Whilst working at the alimentary canal of this worm, I was 

 surprised to come across numbers of large ciliates living com- 

 mensally in the gut. They were usually found in the middle 

 region, and not at the posterior or anterior ends of the gut. 

 There were often so many of them present that they almost filled 

 the cavity of the intestine. Many of these ciliates showed 

 signs of budding ; it was quite a common occurrence to come 

 across a ciliate with anything from one to six buds at the hinder 

 end, and the pressure of the cover-slip was only required to make 

 one or two of the buds break off" and swim about independently. 



The largest and commonest of these ciliates living in 

 the gut was Mesnilella fastigiata (3). The length of this 

 ciliate varies considerably, but an average length is "3 to 

 •4 mm. It is elongated and cylindrical in shape, with a 



