HOMER W. SMITH AND G. H. A. CLOWES. 



effect of acid and alkaline sea water both in respect to activation 

 and to the subsequent fertilizability after varying exposures. 

 The worms were removed from their tubes as soon as they were 

 brought into the laboratory, and the males and females were 

 placed in separate dishes with running sea water. Before use the 

 females were rinsed well with tap water, then with sea water, and 

 placed in about 50 cc. of sea water in a finger bowl. The egg 

 sacks were cut and the ovaries removed and gently teased apart. 

 After about 15 minutes when all the ripe eggs were shed, the tis- 

 sue fragments were picked out, the egg suspension filtered through 

 cheese cloth and the eggs concentrated by centrifuging. Because 

 of the small quantity of eggs available, it was necessary to re- 

 duce the volume of the pH solutions to 50 cc. Equal quantities of 

 maturated eggs were added to each of the pH solutions ; at various 

 intervals portions of these eggs were transferred to two dishes of 

 sea water, only one of which was inseminated. Fresh sperm from 

 one male were obtained when desired by cutting a new sperm sack 

 and allowing the escaping sperm to accumulate in a small quantity 

 of sea water. 



The activation of Chcetopterus eggs by H-ions is illustrated in 

 Fig. 3 by the dotted line. The activation is most intense at pH 

 5.8 and diminishes rapidly on either side of this point, practically 

 disappearing at 5.0 and 6.6. If the eggs are left at pH 5.8 polar 

 bodies are extruded in 30 to 50 minutes, and about 50 per cent, or 

 more will at the end of two or three hours show marked ame- 

 boid movement and extensive fragmentation by budding. The 

 egg flows spontaneously into several unsymmetrical pseudopodia 

 and these in turn develop smaller extrusions, many of which bud 

 off into small spherical fragments. Nuclear division apparently 

 does not always precede this fragmentation, which seems to be 

 largely a result of the ameboid activity of the cortex. If, how- 

 ever, the eggs are exposed for one or two hours to the acid solu- 

 tion and then returned to sea water, 50 per cent, or more will 

 undergo one or two segmentations which more or less simulate the 

 divisions of the normally fertilized egg. They do not develop be- 

 yond the two- or four-cell stage, however, and in the majority of 

 instances the cleavages are irregular and the blastomeres tend to 

 separate. If the eggs are returned to sea water after shorter ex- 





