1 



Qatty Marine hahoratory, St. Andrews. 237 



region of this coat secretes albuminoid substances, fat, and 

 urinary products. As will be shown subsequently, such is 

 a misajjprehension of the structure of the peritoneal surface, 

 probably owing to the condition of the accomplished Belgian 

 author's material. 



In connection with Gilson's opinion, for it is nothing 

 more, that the liypodermic canals in the sixth segment are 

 genital ducts, it is notew^orthy that Arnold Watson observed 

 the reproductive elements in Owenia issuing from two pores, 

 to the right and left of the anus, a portion of the posterior 

 end of the bod}' projecting from the anterior aperture of the 

 tube. Thus Gilsou's theory of the advantages of the ante- 

 rior opening of the hypodermic tubes (his genital ducts) 

 lapses, were it only by the thrusting out of the much more 

 delicate tail anteriorly. 



Ogneff"^ (1899), working at the Naples Station, took up 

 the subject of Gilson^s "'cellules musculo-glandulaires^' in 

 Owenia. In his prepax'ations he found within the muscular 

 \-d\ev of the body-wall a protoplasmic and cellular layer 

 w liich lined the coelom. In the muscle-fibres of the longi- 

 tudinal coat themselves were spindle-shaped cells with nuclei, 

 as Schwalbe first described in the muscles of worms and 

 lamellibranchiate mollusks, and also on the surface of the 

 muscles in a protoplasmic layer. Over these, however, is a 

 layer of peritoneal cells, which are cup-shaped, with rounded 

 inner or deeper surfaces and flattened surfaces toward the 

 cceloni, w ith an oval nucleus, fat, and granules like the white 

 of egg in the protoplasm. A fine protoplasmic network 

 stretches from these amongst the muscle-cells. He thought 

 there were as many as fifteen to twenty peritoneal cells to 

 one muscle-cell. He did not consider that Gilson's " muscle- 

 gland-cells" existed in Oivenia, the misapprehension being 

 due to the less elaborate methods of preparation and section- 

 making. 



In 1900 a very interesting paper on Oivenia fiisiformis 

 was communicated to the Linnean Society by Mr. Arnold 

 Watson t, whose observations on the living animals are 

 noteworthy. His description of the lip-organ and its func- 

 tions, the occurrence of a prostomial pore^ the discovery of 

 theemi-sion of the sexual elements through twocoelomo-ducts 

 (anal pores), the structure and repair of the tubes, and the 

 rearing of the ova to the Mitraria-stnge are the chief features 

 of this contribution to the life-history of the species. 



• Biol. Centralblatt. Bd. xix. p. 136. 



+ Journ. Linn. Soc. vol. xxviii. p. 259, pi. xxii. 



