282 REPORT— 1903. 



Occupation of a Table at the Zoological Station at Naples. — Report of 

 the Committee, consisting of Professor G. B. Howes (Chairman), 

 Mr. J. E. S. Moore (Secretary), Dr. E. Eay Lankester, Professor 

 W. F. R. Weldon, Professor S. J. Hickson, Mr. A. Sedgwick, 

 and Professor W. C. McIntosh. 



Report on the Occupation of the Table during February, March, April, 



and half of May, 1903. 



The Oocyte of Tomopteris. By William Wallace, B.Sc. 



At Naples I studied the earlier stages of the oogenesis of Tomopteris 

 oniscifortnis, Esch., and particularly the changes in the germinal vesicle 

 during the growth of the oocyte. 



Since Eschscholtz discovered this species in 1825, several naturalists, 

 including Claparede, Vejdowski, Carpenter, and Fullarton ' (1895), have 

 dealt with the genital products of Tomopteris, and have described the 

 more obvious features of the oogenesis, such as the following : — 



1. The origin of the ovaries in the rami of the parapodia by pro- 

 liferation of cells of the coelomic epithelium. 



2. The detachment from the ovary and discharge into the ccelom of 

 balls of cells. One cell of each cluster, increasing in size, becomes the 

 oocyte, while the remainder — some half dozen or so — continue attached 

 to the larger cell, and constitute the ' nurse-cells.' 



3. The growth of the oocyte (apparently) at the expense of the group 

 of nurse-cells, which is soon no more than a cap or small appendage at 

 one pole of the egg. These nurse-cells finally degenerate and disappear. 



Such phenomena are not diagnostic of the oogenesis of Tomopteris, 

 but have been described for other Polychfetes, such as Ophryotrocha 

 (Korschelt -), Onuphis (Bergmann ^), &c. 



The cytological changes accompanying the growth and maturation 

 of the egg of Tomopteris do not appear to have been studied hitherto. 

 Some observations on this head may accordingly be of interest. 



The material at my disposal was, thanks to the kindness of Dr. Lo 

 Bianco, tolerably abundant. The species, however, does not seem to be 

 so plentiful here as, for example, at St. Andrews, where, during certain 

 seasons, large quantities are found in the tow nets. Neither were the 

 ripe female specimens so large at Naples. All that I had to deal with 

 were under a centimetre in length, whereas at St. Andrews the specimens 

 commonly attained a length of two or three centimetres (if I remember 

 rightly). 



In all the Neapolitan specimens I examined numerous gregarines 

 occurred, mostly in an encysted condition in the epithelium of the gut. 



I studied the eggs in the fresh state, when, like the whole body of 

 Tomopteris, they are transparent. I also studied them in serial sections 

 of fixed material. 



' Fullarton, Zool. Jahrb. (Spetiffel's), Morph. Abth., viii. Bd., 1895. 



^ Korschelt, Zeit.fiir wigs. ZooL, Bd. Ix. 1895. 



' Bergmann, Zeit.fiir miss. Zool., Bd. Ixxiii., Hft. 2, 1902. 



