312 



Proceedings of Indiana Academy of Science 



Table 1 shows a series of the first type that was taken in 1922 at 

 the littoral station. The data columns give: (1) the water temperature, 

 (2) the amount of oxygen necessary to saturate water at that tempera- 

 ture, (3) the amount of oxygen present in cubic centimeters per liter, 

 and (4) the per cent of saturation. On July 20 it was slightly cloudy 

 and in consequence slight changes occurred. The temperature increased 

 1.5° C, the oxygen decreased slightly (.08 cc. per liter) the per cent 

 of saturation increased 2 per cent. On the other four days the amount 

 of oxygen, the temperature, and the per cent of saturation increased. 

 The average increase in temperature was 4.3° C, the increase in oxygen 

 was 3.33 cc. per 1. and saturation increased 72 per cent. While the 9:30 

 observations were not the minimum for the 24 hours yet the amount 

 present at 9:30 on July 25 and 26 was greater in each case than it was 

 en the preceding evening at 4:15. 



TABLE I. 

 Data Obtained from Semi-Daily Observations at Winona Lake, Indiana 



We have secured three sets of serial observations taken as follows: 

 9 a. m. to the folowing 8 p. m. ; 6:30 a. m. to 11:30 p. m.; and from 

 6:30 to 8:30 p. m. The first is for the littoral .station alone. The other 

 two are for both .stations in parallel. 



The pulse in Series 1 (fig. 1) reached its maximum at 6:30 p. m. 

 The notch in the oxygen curve at 3:00 was due to clouds between 12 

 noon and 3 p. m. At 3 p. m. it was again clear and remained .so. At 

 6 p. m. the temperature had fallen 2° C, and the oxygen had increased 

 slightly more than 2 cc, both of which facts tended to increase the per 

 cent of saturation. Sometime between 9 p. m. and 12 p. m. the per 

 cent of saturation became less than 100 per cent and remained so 

 until 8 a. m. the next day when it was exactly 100 pei- cent. 



The lowe.«t temperature was at 3 a. m. although it probably became 

 slightly lower between that hour and sunrise. 



In Series 2 (fig. 2) the maximum occurred at 3:30 p. m. at the 

 pelagic station and at 5:30 at the littoral. The amount of oxygen at 

 the pelagic station at 6:30 p. m. exceeded the amount at the littoral sta- 

 tion. This condition was again reached at 9:30 p. m. and 11:30 p. m. 

 Between 6:30 a. m. and 9:30 p. m. there was more oxygen at the lit- 



