124 REPORTS ON INVESTIGATIONS AND PROJECTS. 



A number of large corroded coral rocks were placed in live-cars, which 

 floated upon the ocean, while others were placed in a box fastened to the 

 ground, and in which the tide rose and fell. One of the floating live-cars was 

 open to the light both day and night, and the worms in the rocks in this 

 car swarmed normally on the morning of July 22. As these rocks had been 

 in the car for a month floating upon the sea, and not subject to rise and fall 

 of tide, it is evident that the worms do not respond to a condition of the 

 tide, but must respond either to the light or the position of the moon, or 

 to some emanation from the moon, or to all three. 



Another large floating live-car was covered every night with a wooden 

 cover for a month previous to the swarm, so as to exclude the moonlight. 

 Unfortunately it was darkened also during the day for about a week of this 

 time, during the enforced absence of the writer. None of the worms swarmed 

 in this car, but on cracking open the rocks it was found that although many 

 of the worms were full grown, they had not become sexually mature. Sex- 

 ually immature worms never swarm ; hence the experiment is inconclusive 

 and must be tried again, taking care to allow sunlight to fall upon the rocks 

 each day. 



The worms in a darkened box in which the tide rose and fell did not swarm. 

 Evidently light is necessary for the worms to become sexually mature, and 

 this seems somewhat remarkable, as they live hidden away in the dark crev- 

 ices of the rocks. It is probable that the worms respond to the position of the 

 moon, for the Japanese palolo, according to the Izuka, swarms within three 

 days after the day of the new and the full moon, and thus evidently does not 

 respond to a certain intensity of moonlight. Moreover, the Atlantic and 

 Pacific palolo worms swarm either in clear or in cloudy weather. 



The laboratory was closed for the season on July 26, and the 

 Physalia was brought up to Miami, Florida, and laid up in the fresh 

 water of the Miami River, where she will be secure from the most 

 severe storm. I take pleasure in reporting that the yacht and labora- 

 tory, and other property of the Carnegie Institution intrusted to my 

 care, are in good order. 



It is with great pleasure that we acknowledge our debt of grati- 

 tude to Captain George P. Colvocoresses, U. S. N., and Captain 

 William H. Buhler, U. S. N., successively commandants of the Key 

 West Naval Station, for their many acts of kindness and cordiality 

 displayed toward all connected with the laboratory. Without this 

 generous aid the laboratory could not have been efficiently main- 

 tained. 



