EGG-LAYING HABITS OF AMPHITRITE ORNATA VERRILL. 33! 



the afternoon. I believe this tendency to deposit eggs in the 

 afternoon or early in the evening may be accounted for in the 

 following way. When low tide occurs near mid-day or early 

 afternoon, the sand flats are more exposed and reach a higher 

 temperature than under ordinary circumstances. Metabolic 

 changes are undoubtedly more active at these times and for a few 

 hours immediately following. As a consequence, if the worms 

 behave in their tubes as they do in the first few hours in the lab- 

 oratory, the eggs are laid on a rising tide about the time of slack 

 water. This time would be favorable for fertilization on account 

 of the" absence of strong currents. Some five hours later, the 

 young blastula is ready to swim, as shown in a previous paper 



('06). 



TABLE II. 



Shows time at which eggs and sperm were deposited in reference to spring tide. 

 Also the number of collections made in reference to the same period. 



In all sixty-five experiments are here recorded, scattered 

 pretty evenly throughout the summer from June 24 to August 

 23. In 1902 I was working on the unfertilized egg and few 

 attempts were made at fertilization ; hence the data are rather in- 

 complete for that year. At first glance my data do not appear very 

 significant, but one readily notices a general tendency for the ovi- 

 position to occur near the time of spring tides. This is especially 

 true in those experiments where I found mature sexual products 

 in greatest abundance. For example, in 1902 the best success in 

 fertilization occurred on July 7, two days after new moon ; in 

 1903 the best results obtained for the season were at the time of 



