departme;nt of marine biology. 125 



He also found that various marine animals are much more sensitive to 

 concentrated than to diluted sea-water, and in this research he made a series 

 of observations upon the regeneration of Cassiopea in diluted, normal, and 

 concentrated sea-water, the concentration being accomplished by partially 

 evaporating the normal sea-water. He found that regeneration is more rapid 

 in slightly diluted than in normal sea-water. 



Prof. E. W. Gudger studied the anatomy and breeding habits of several 

 species of sharks and rays, paying special attention to the nurse shark. He 

 also made general observations upon the habits of the reef fishes, and it is 

 hoped that the laboratory may be able to afford him every possible facility in 

 this work, for but little is known of the breeding habits of the coral-reef 

 fishes, and Professor Gudger's success in the study of many hitherto unde- 

 termined or obscurely known habits of fishes leads us to hope that he will 

 make some equally important discoveries at Tortugas. 



Dr. T. Wayland Vaughan found that the reef corals feed upon the animal 

 plankton, but not upon the plant life of the ocean. He found that corals 

 require to be fed more constantly and more copiously than had hitherto been 

 supposed, and that we can readily distinguish a well-fed from an underfed 

 coral by its appearance. He also tested the effects of exposure to air and 

 found that reef corals are remarkably tenacious of life when dried, thus 

 accounting for the fact that the living reefs withstand exposure over wide 

 areas at the low tide of the spring tides. Dr. Vaughan also remeasured and 

 photographed his many specimens of corals that are growing in various situ- 

 ations, and which are expected to furnish an idea of the average rate of 

 growth of corals upon the reefs. 



Prof. John B. Watson expected to determine the limits of the visible spec- 

 trum for the noddy and sooty terns of Bird Key. This may possibly have 

 some bearing upon the actuating cause of the migratory or homing instincts 

 in these sea-birds. Accordingly, he brought a heliostat and spectroscope with 

 him from the Johns Hopkins University, and with his own hands made an 

 excellent dark-room in which to perform the experiments, in the meantime 

 rearing the young birds with all possible care. It was found, however, that 

 the gasoline engine at Tortugas could not generate a non-flickering electric 

 light, and Professor Watson therefore took the young birds to Baltimore, 

 hoping to study them under the best possible conditions of stimulation in his 

 laboratory. Unfortunately, however, they died one after another before he 

 could obtain decisive results, and the experiment must be tried over again. 

 It is hoped that with improved facilities this experiment may be conducted 

 at Tortugas next year. The great care and labor involved in rearing the 

 young gulls renders it doubly regretful that Professor Watson's well-planned 

 experiments were doomed to end in a temporary disappointment. 



Alfred G. Mayer took many kymograph records designed to illustrate the 

 behavior of the pulsating Cassiopea when subjected to varying concentra- 

 tions of the several cations of sea-water and to differing temperatures, the 



