334 JOHN w. SCOTT. 



opening of the tube and actively explore the vicinity for a dis- 

 tance of several inches. Their food consists of small bits of 

 organic matter carried to the mouth through the action of cilia. 

 One result of the feeding activity is seen in the fact that the 

 immature eggs or sperm grow and mature very rapidly during 

 the last few days immediately preceding the sexual period. 

 Undoubtedly, this increased activity of the organism is stimulated 

 by the higher temperature of the sand flats at the time of spring 

 tide. The alternate increase and decrease in the depth of the 

 water, thus altering the pressure, probably has some influence 

 and the food supply at this period is certainly more abundant. 

 We must conclude therefore that the influence of the tides or 

 moon is entirely secondary. The sexual activity in tliese ^cvorms is 

 closely associated with a similar rhythmical period of greater 

 bodily activity ; and this greater bodily vigor of the animal is 

 induced by conditions t/iat depend upon the tides. Furthermore, 

 the periodic sexual reflex has acquired a sort of physiological 

 basis in the organism, for the worms deposit sexual products 

 normally, when removed from the influence of the tide. Still 

 this reflex has not become a habit in the animal, at least not a 

 strong one, for if a worm does not deposit its products within a 

 few hours after being captured it rarely does so, and then not 

 later than the following day. 



II. METHOD OF EGG-LAYING. 



The eggs of Amphitrite break loose from the matrix of the 

 germinal epithelium in early stages of development and complete 

 their growth while floating free in the ccelomic fluid. In a 

 single worm they are usually found in the various stages of 

 development. When first collected, all worms go through with 

 a series of rhythmic movements of the body. When performed 

 in the tube, these movements are evidently for the purpose of 

 aeration, and they are kept up for some hours after the animals 

 are removed from the tube, gradually diminishing in intensity. 

 Each series of movements begins as a contraction near the pos- 

 terior end of the body and travels forward ; a second contraction 

 follows, and frequently a third has begun before the first has 

 disappeared. Between the contractions are wave-like enlarge- 



