152 SOME FURTHER RESEARCHES 



its full length. If we consider that the process of cuticular secre- 

 tion is one that occurs on the external surface of the secreting 

 epithelial layer, it will be reasonable to think that the secretion of 

 a seta (as an analagous process) also takes place on the surface of 

 the cell by which it is produced. Now, to all appearance the seta 

 is placed in the midst of the cell (see Fig. 2). I think, however, that 

 the cell-wall is really invaginated, the invagination taking the form 

 of the forked tip of the seta, and that the cuticular deposit takes 

 place on the surface of this invagination, as shown in Fig. 3. As 

 the seta grows, the invagination deepens, the tip of the seta 

 advances within the cell, and more cuticular substance is deposited 

 at the base, i.e., at the mouth of the invagination. In time the 

 growing seta either forces its way through the wall of the cell 

 which gave it birth, or which is, I think, more likely, the cell-wall 

 adheres closely around it, as in Fig. 5. It ultimately also penetrates 

 the cuticular covering of the worm. 



With regard to the method of oviposition, I am enabled to state 

 that the egg capsules which I have drawn in Plate 34, Fig. 16, of 

 vol. ii., are formed around the worm, i.e., around the glandular 

 clitellus which encircles the generative segments. After its forma- 

 tion, the ova and spermatozoa are passed into it, and it is then 

 slipped over the head of the worm, and thus becomes detached ; 

 the ends becoming closed in some unknown manner. How the 

 ova make their way into it, i.e., whether they find exit by an oviduct 

 surrounding the vas deferens, as I have stated was Claparede's 

 opinion, or by any other method, I do not as yet know ; but the 

 presence of spermatophores in the seminal receptacles must be 

 regarded as the normal condition of sexual maturity — i.e., they are 

 introduced into these cavities, they remain there, and after a period 

 of vital activity they perish there, unless called into functional 

 activity by the act of oviposition, when they find their way into 

 the capsule as it passes over the mouth of the receptacle, and so 

 obtain access to the ova. Whether they enter the capsule, however, 

 as spermatophores, or whether the spermatic filaments from them 

 only do so, remains yet in uncertainty. 



I have not yet been able to follow out the various stages of 

 embryonic development, but have on one or two occasions seen 

 the birth of young worms, or rather their escape from the capsule, 



