416 PROCEEDINGS OF THE AMERICAN ACADEMY. 



lancelets were obtained from the Flatts Inlet, which leads from the 

 outer waters to Harrington Sound. This inlet, through which a 

 strong tidal current is almost always running in one direction or the 

 other, contains long stretches of coarse coral and shell sand, and it 

 was in these sandy stretches, especially near the open mouth of the 

 inlet, that the lancelets were found in abundance. They likewise 

 occurred, as recorded by Barbour (;05, p. 110), in the sandspit near 

 the inner end of the inlet opposite Hotel Frascati, but they were by no 

 means so abundant there as in the coarse shelly stretches which were 

 near the outer mouth of the inlet and at low tide were still covered 

 by several feet of water. From this source, with the assistance of 

 some of the negro boys from the neighborhood, a daily supply of large, 

 vigorous lancelets was obtained, and, as the animals were available in 

 the laboratory almost immediately after they were caught, the con- 

 ditions were unusually favorable for a study of their sensory reactions. 

 For experimental purposes these lancelets proved to be very satis- 

 factory. They could be kept for a number of days in a vigorous 

 condition in large glass jars containing sea water and some coral sand, 

 provided that from time to time the sea water was renewed, and their 

 resistance to the adverse conditions of operative experiments was as 

 great as that of B. lanceolatum (Haeckel, '80, p. 141). 



In the shoal water of Harrington Sound northwest of Trunk Island 

 the expeditions from the laboratory on several occasions dredged 

 Andrew's lancelet, Asymmetron lucayanum Andrews, but this species 

 was not sufficiently accessible nor abundant to make it a satisfactory 

 form for experimentation. In testing the sensory reactions of the 

 lancelets I therefore limited my work to the more common species, 

 Branchiostoma caribbaeum, and attempted to determine the re- 

 actions of this species to light, to heat, and to mechanical and chemical 

 stimuli. 



2. Light. 



Although the sensitiveness of amphioxus to light was known to 

 Costa ('39, p. 4) 2 and many other earlier investigators, and has since 

 been generally admitted, much difference of opinion has been expressed 

 as to the degree of this sensitiveness. Willey ('94, p. 10) declares that 

 " if a lighted candle is carried into a dark room in which amphioxus 

 are being kept in glass jars, the excitement produced among the small 



2 The statements concerning the reactions of amphioxus to lisht given by 

 Costa do not occur in his first account of this animal (Costa, '34, p. 49) as 

 cited by Krause ('97, p. 513), but in his later and more lengthy description 

 (Costa. '39, p. 4). 



