AiniFlCIAF- ("ULTUKE OF MARINE PLANKTON 0RC4ANISMS. 423 



occupied in development. On August 29tli, 1907, eggs of 

 Pomatoceros triqueter were fertilised in animal-charcoal 

 Berkefeld water, and some pure culture of Nitzscliia clos- 

 terium var. added. The larvae fed well, and on October 1st 

 (i.e. thirty-three days after fertilisation), a great number 

 had fixed on the sides of the jar and made quite normal tubes. 

 A constant stream of the ordinary aquarium water was then 

 allowed to run through the jar, and the worms continued to 

 gi'ow and flourish, reaching a large size, and are still alive and 

 healthy (November, 1909). A similar result was obtained 

 from the same batch of eggs by feeding on a pure culture of 

 a flagellate infusorian. Temperatures during these two 

 experiments were between 15° and 19° C. 



Chsetopterus variopedatus. — Four experiments were 

 made with this species. The food which gave most promise 

 of success was the diatom Nitzschia closterium var. 

 Larvae from eggs fertilised on July 20Lh, 1908, fed on this 

 material lived until October oOth, and reached an advanced 

 stage. They did not, however, adopt the adult habit and 

 form tubes. Two larvEe were also reared to an advanced 

 stage by using flagellates, and, in later stages, the diatom 

 Skeleton em a costatum as food. 



Sabellaria alveolata. — One experiment only was made 

 with this species, on eggs fertilised on July 19th, 1908. The 

 eggs were fertilised in ''outside" water, and the larvas 

 subsequently ti'ansferred to jars containing animal-charcoal 

 Berkefeld aquarium water. They were fed on a pure culture 

 of Nitzschia closterium var., and kept healthy and active, 

 and developed well until nearly the end of October, when, 

 simultaneously with a sudden drop in temperature from 15° 

 and 16° C. to 12° and 9 C, they sank to the bottom of the 

 vessel, and in about three days were all dead. Temperatures: 

 During July and August the temperature kept fairly constant 

 at about 17° C, with a range from 15° to 19° C. During 

 September it was generally about 15° C, and continued at 

 about this level until the fall in the middle of October. 



Archidoris tuberculata. — A good many trials have 



