1 84 Phylum A nnelida 



Bibliography 



Lillie, F. R., and Just, E. E. 1913. Breeding habits of Nereis limbata at Woods 



Hole, Mass. Biol. Bull. 24:147. 

 Just, E. E. 1922. On rearing sexually mature Platynereis megalops from eggs. 



Amer. Nat. 56:471. 

 Wilson, E. B. 1892. Cell lineage of Nereis. J. Morph. 6:361. 



A METHOD FOR REARING NEREIS AGASSIZI 

 AND N. PROCERA 



John E. Guberlet, University of Washington 



THE writer has reared two species of Nereis to sexual maturity in the 

 laboratory by the use of the following method. One species, Nereis 

 agassizi, was reared to sexual maturity during each of two consecutive 

 years and in the third attempt the larvae were maintained for a period of 

 nearly 14 months but due to unfortunate circumstances did not reach 

 sexual maturity. A second species, Nereis procera, was successively cul- 

 tured in the laboratory for a year. At the end of that period the worms 

 had reached sexual maturity. 



While the worms are "swarming" at the surface in their seasonal 

 spawning it is a comparatively easy matter to capture both males and 

 females. Better results may be obtained if the males and females are 

 kept separate during capture and transfer to the laboratory. They 

 should spawn in separate dishes in sufficient seawater to keep them well 

 covered and to maintain a fairly even temperature. A small amount of 

 water containing spermatozoa is added to the eggs and thoroughly mixed. 

 Care should be taken not to use too great excess of spermatozoa. The 

 dish containing the fertilized eggs should be allowed to stand for a few 

 minutes and then be emptied into a larger container (battery-jar) con- 

 taining 2 or 3 liters of seawater. This jar is placed in running water or in 

 a suitable location to maintain a fairly constant temperature. The degree 

 of temperature best suited to a particular species would seem to be that 

 of the environment from which the adult worms were taken. After the 

 eggs have settled to the bottom, as much of the water as possible should 

 be siphoned off to remove the excessive spermatozoa from the culture and 

 fresh seawater should be added. Polar bodies begin to appear after 1 

 to 1% hours and cleavage starts after 2% hours. The cleavage rate is 

 usually fairly rapid and movement of the larvae begins in 12 to 15 hours. 

 The trochophore stage is reached in about 36 to 48 hours and larvae with 

 three pairs of setigerous appendages appear in between 3 and 4 days. 

 It is highly important that the temperature be kept constant. The 

 water should be changed daily and agitated at least once each day to 

 provide aeration. When the larvae have developed setigerous append- 

 ages they will soon be provided with jaws and are then ready to begin 



