12 IT. S. BUREAU OF FISHERIES. 



Bacteriological examination of the terrapin by R. L. Barney, 

 director of the Fairport (Iowa) station, and A. Scorpio, temporary 

 assistant, has revealed in each case a characteristic organism, a diplo- 

 bacillus, varying considerably in size under different conditions. 

 Biochemical tests of the organism have been made, and morphologi- 

 cal and staining characteristics have been noted. The germ finds 

 lodging in the epithelial tissue of the epidermis and in connective 

 tissue beneath. Cultures of the organisms have been isolated and 

 injected into healthy individuals producing death in some cases in 

 a short time. Observations on the effect of temperature, light, salin- 

 ity, and drying out of the terrapins in connection with the preva- 

 lence of the disease haA^e been recorded. Further studies projected 

 may develop methods of prevention of transmission of the disease 

 or of a remedy. 



STUDIES OF RIVER, LAKE, AND SEA, 

 CHESAPEAKE BAY. 



The regular cruises planned for the hydrographic and biological 

 survey of Chesapeake Bay were completed in June, 1921, but two 

 additional cruises, one in January and another in March, 1922, were 

 made in order to obtain additional data regarding the hydrogen-ion 

 concentration or alkalinity of the water during the winter and 

 spring as well as data concerning the occurrence of young fish and 

 the movements of fish in general. As a result of these last two 

 cruises and the cruise of June. 1921, evidence was obtained from 

 tests on the 24-hour stations; first, that there are indications of a 

 diurnal variation in the hydrogen-ion concentration of the Chesa- 

 peake water (less alkaline usually during the night) ; second, that 

 the water is inclined toward acidity near the mouth of the Patapsco 

 River and that it becomes more alkaline passing toward the Capes; 

 third, that in the summer the alkalinity decreases rapidly passing 

 from the surface to the bottom; and, fourth, that there is almost 

 no difference between the degree of alkalinity of surface and bottom 

 water during the wintertime. 



During the past year a study of the hydrographic data obtained 

 in 1915-16 and 192(>-1922 show that the mixing of ocean and river 

 watere is not complete, that the more saline water is found at the 

 bottom, and that the waters near the eastern shore seem to have a 

 greater amount of salt than those along the western shore, at least 

 in the lower half of the bay ; and that usually the temperature of 

 the water increases with the depth during December and January, 

 that it decreases with the depth during April, June, and July, and 

 that in March and September there is litne or no difference between 

 the temperature of the surface and the bottom. 



The current meter observations every 1| hours on the 24-hour sta- 

 tions yielded the interesting information regarding tidal currents 

 that at times in any one locality the water at the bottom may be 

 moving up the bay and the water at the surface down tlie bay, and 

 that at other times the surface water may be almost stagnant while 

 the bottom water may be moving with considerable velocity either 

 up or down the bay. 



