1919 Gail; on Fucits and Hydrogen Ion 293 



practically all of the cells were broken down and the plants were becom- 

 ing frayed. The effect on the Fucus plants in seawater having pH values 

 of 7.0 and 7.2 was similar, but three or four weeks were required to bring 

 about the same results. 



Those plants in seawater having pH values of 7.4, 7.6 and 7.8 showed 

 little or no effect except that the growth was somewhat inhibited. There 

 appeared to be a physiological adjustment to some extent, at least tempo- 

 rarily. Since Fucus is rarely found in seawater having a pH value as 

 low as 7.4, and this for only a short period in the early morning, it would 

 seem that it might be a matter only of time until the plants in seawater 

 having this pH value and possibly the plants in seawater having a pH 

 value of 7.6, woiild show results similar to those in the lower pH values. 



The plants in seawater having a pH value of 8.0 to 8.2 had increased 

 on the average 1 cm in length, and about 80 per cent of them were 4-lobed. 

 In one jar containing seawater having the same pH value, the Fucus plants 

 had not grown as much. These had increased in length only about 7 mm 

 but the same percent of them were 4-lobed. There was no cause apparent 

 for this difference since the conditions were the same and they had received 

 the same treatment. There may have been some difference in the vigor of 

 the plants but they appeared the same at the beginning of the experiment. 

 At the end of 1 1 weeks the experimental plants were compared with those 

 on the shore from which they were taken. The growth was practically 

 the same. Those in the jars having seawater with a pH value of 8.0 to 

 8.2 were slightly lighter in color. The cause was undoubtedly due in a 

 large degree to the difference in temperature, as will be explained later. 



The P'ucus plants in seawater having a pH value of 8.4 became abnor- 

 mally darker after about 4.5 weeks and remained darker thruout the entire 

 time. They showed an average increase in length of 3 mm at the end of 

 11 weeks. Two of the 30 plants in the jars containing seawater having a 

 pH value of 8.4 had become 4-lobed. 



The Fucus plants in seawater liaving pH values of 8.6 and 8.8 became 

 very dark at the end of the first week. They also appeared more leathery 

 and soon took on a reddish tinge. A microscopic examination after 8 weeks 

 showed all the cells to be dead, except those in the interior part of the 

 thallus. The protoplasm was brownish in color and many of the cell walls 

 near the outer margin were collapsing. No growth liad taken place at the 

 end of 11 weeks and very few cells appeared normal. 



The results from the set having the temperature range from 10.5° to 

 13°C will now be considered. In jars containing seawater with pH 

 values of Q.Q, 6.8 and 7.0 the results were practically the same as in the 

 two previous sets except in degree and in that a longer period of time was 

 required. No effects were noticeable until on the 8th day on the Fucus 



