1901.] FKOM BRITISH EA,ST ArBICA. 351 



this worm a peculiar compact body, " whose structure I was 

 unfortunately unable, on account of the unfavourable preser^ation 

 of the material, to understand. The whole interior of this body 

 appeared to be formed of a structureless granular mass. Aji 

 outer .... layer encloses this mass. This outer layer seemed to 

 me to possess a celhdar structare^' ^. Michaelseu then suggested 

 the possibility that this body A\as an embryo— a by no means un- 

 natural suggestion in Aie^' of its size and appearance in a badly 

 preserved specimen. I emphasize, however, the remark that the 

 outer layer appeared to be of a cellular nature ; as this opinion 

 was no doubt founded upon the observation of the deeply staining 

 bodies, which, I. think, must be the nuclei of the cells lining the 

 spermatheca. I am far from asserting, however, that the outer 

 case of the spermatophore is a layer of living cells. This may be 

 so ; but in the meantime I should regard it rather as produced by 

 the broken down debris of the cells of the spermatheca, including 

 liberated nuclei, all of which will possibly Icse their characters as 

 the spermatophore gets riper. The facts, however, so far do not 

 permit, as I think, of a decisive statement of opinion. So far, 

 then, the case of the spermatophore appears to be a pi'oduct of the 

 spermathecal sac where it is found. At the head-end of the 

 spermatophore the case is filled with the dark granules already 

 mentioned, which are particularly thickly clustered along the 

 narrow beak. The cells of the spermathecal sac contain no 

 granules of this character. They are like those of the chloragogen 

 cells ; but in this particular worm I noticed no chloragogen cells 

 which might serve to explain the origin of the granules. The 

 only place where there were cells filled w ith such granules were 

 the innermost layer of cells of the spermiducal gland. 



The e\ idence seems to me therefore to be strongly in favour of 

 the view that the Avall of the spermatophore in the head-region is 

 deri\ed from materials existing in the spermiducal glands. The 

 final plug of granular matter must therefore be added after the 

 spermatozoa have been injected into the spermathecal sac from 

 the male orifice. There is a remarkable analogy here with the 

 (or a) supposed use of the prostatic fluids in mammals. It has been 

 held that it serves as a plug to retain the sperm in the female 

 organs, and it may apparently harden into a definite plug usefiil 

 for that purpose. The use of spermatophores of the type described 

 here may be largely to prevent the sperm from wandering and 

 from finding its w ay out of the receptacle intended for its storage. 

 But it must be remembered that we are at present in absolute 

 ignorance of the way in which fertilization is effected in these 

 Annelids. 



(4) On the Ovaries, Oviducts, and Sperm-ducts of Stuhlraannia. 



Although the main features in the structure of this Eudrihd 

 genus have been amply elucidated by the careful observations of 



^ The italics are mine, 



