90 



THE AMERICAN NATURALIST 



[Vol. LIV 



Some distinct indications were had of a seasonal variation in 

 p H of the enclosed waters, hut tidal and other diurnal complica- 

 tions in the lagoons would make it necessary to institute a. long 

 series of studies for the complete description of this phenom- 

 enon. 10 The general fact was quite apparent that the "inside" 

 water (i. e., water within the sounds) was less alkaline than the 

 "outside" water over the reef flats, the latter likewise less alka- 

 line than the open ocean. Eight sets of estimations gave the 

 p H of water taken at flood tide just beyond the outermost reefs to 

 the west and northwestward of Bermuda, as 8.25 (21°-23°), at a 

 salinity of 36.4 ± per mille, agreeing with that found by other 

 observers for Atlantic water in this general region. The p H of 

 the "outside" water was at different times observed to lie between 

 8.09 and 8.23. Within the sounds, however, the range noted was 

 from 7.95 -4- to 8.15. The case of Harrington Sound, an almost 

 completely enclosed body of water, is the most interesting. The 

 waters of this lagoon are in communication with the outside sea 

 through but one surface channel, a narrow cut at Flatt's Inlet; 

 there is also a small amount of subterranean communication. 

 Several specific examples will make clear the differences found. 

 The figures refer to samples taken with a tube of pyrex glass 

 from a depth of 2-3 feet below the surface. Samples obtained 

 from depths of several fathoms ran in about the same way. 

 Sept. 13th, 1917. 



Great Sound, 9:40 A.M. Tide ebbing, Water temp. 26.9°; air 27.5° p H 8.20 



Harrington S.I.. ]0 : r>5 A.M. Tide ebbing, Water ten, p. 27.4°; air 27.8° 

 p H 8.06 

 Nov. 22d, 1917. 



Great Sound, 9:05 A.M. Tide low, Water temp. 19.8° ; air '24.0° p H 8.08 

 North shore, 9:40 A.M. Tide low, , p H 8.20 



Harrington Sd., 10:45 A.M. Tide low, p H 7.95 



Such results obviously speak for the view that the solution 

 of limestone by the sea within such lagoons as Ilarrmutnn 

 Sound must be reckoned with. Exactly how important a part 

 it plays in the final adjustment of the land form can not, of 

 course, be said. The color of the sea water, I might note, varies 

 in correlation with the p H . Within the sounds, color-readings 

 on the Forel scale 11 averaged 5.5 (17 per cent, yellow), whereas 



10 Cf. Moore, B., Prideaux, E. B. R., and Herdman, G. A., 1915, Trans. 

 Liverp. Biol. Soc, Vol. 29, p. 233. MeClendon, J. F., 1918, Publ. No. 252, 

 Carnegie Instn. Wash., pp. 213-264. 



11 Steuer, A., 1910, Planktonkunde, xv + 723 pp., 1 Taf. und 365 Abb., 

 Leipzig. [Pp. 84-98.] 



