lOU 



SCIENCE 



[N. S. Vol. XXXVIII. No. 



the one in the sunlight showed a very distinctly 

 less amount of change, but when compared 

 with the control it gave evidence of change. 

 The specimen in the shade was usually more 

 distinctly stained by the neutral red than the 

 specimen in the sunlight, and the solution in 

 the shade was apparently clear after the lapse 

 of fifteen to thirty minutes, while that in the 

 sunlight still distinctly showed the stain in so- 

 lution. As might be expected in some of the 

 experiments, the differences were more distinct 

 than in others. It is taken that the acid reac- 

 tion is due to the elimination of carbon diox- 

 ide. 



A toxic eifect was also evident in the ex- 

 periments in the sunlight due probably to the 

 action of the basic elements of the dye. What 

 this is still remains to be determined. It is 

 apparently due to effect of sunlight on proto- 

 plasm influencing metabolism in such a man- 

 ner that the injurious changes occur; or it 

 may be the effect of sunlight on the interac- 

 tion of the basic dye and protoplasm or its 

 metabolic products. A similar effect is seen 

 in experiments with Paramcecia. In the sun- 

 light there is a greater concentration of the 

 hydroxyl ions which would give an alkaline 

 reaction. The outcome is that hydrolysis 

 takes place which interferes with the normal 

 processes and produces injury to the proto- 

 plasm. In the shade the hydrogen ions have 

 a greater concentration with the more acid re- 

 action. 



As a check upon these results a second set 

 of experiments was made in which the reaction 

 of the sea water was tested in which the speci- 

 mens were placed without the presence of the 

 indicator. In this series equal quantities of 

 sea water, after being tested with the most ac- 

 curate apparatus, were placed with carefully 

 selected individuals in clean glass vessels and 

 arranged, as in the former series, in the sun 

 and in the shade. In this series it was pos- 

 sible to iise the same specimen for the test at 

 different times after exposure for equal inter- 

 vals of time in the sun and in the shade. The 

 results agreed as closely as could be expected 

 with those in the former series. 



In testing the sea water in each case an 



ls/10 solution of hydrochloric acid and an 

 X/10 solution of sodium hydroxide, and phen- 

 olphtalein were used. It was found in a series 

 of ten parallel experiments that at equal inter- 

 vals of time after the lapse of about five 

 minutes from the beginning of each experi- 

 ment up to fifteen minutes, the sea water from 

 the vessels in the sunlight showed less acid re- 

 action than that taken from those in the shade. 

 In four cases the sea water with the specimens 

 in the sunlight remained slightly alkaline, but 

 less so than the normal sea water; four showed 

 a slightly acid reaction, the two remaining 

 were neutral. Of the parallel series in the 

 shade at the same intervals of time, seven, 

 showed an acid reaction, two were neutral and 

 one was very slightly alkaline. Normal sea 

 water is alkaline. It thus appears that the 

 metabolic processes of protoplasm under these 

 different conditions of illumination differ to a 

 degree sufficient to affect the sea water through 

 differences in elimination of the products of 

 metabolism. It is to be remembered that ten 

 or fifteen minutes is usually sufiicient for con- 

 tinuous sunshine to cause a starfish to take up 

 a characteristic fixed position with respect to 

 the light in as protected a place as possible. 



These experiments show that sunlight modi- 

 fies the normal physiological changes taking 

 place in protoplasm, checking some of the 

 processes and probably accelerating others. It 

 appears that the acid and alkaline relations 

 are affected probably through a disturbance in 

 the relations of the hydrogen and the hydroxyl 

 ions. The starfish with one half of its upper 

 surface in the light and one half in the shade 

 moves from the light into the shade because of 

 this interference with its normal physiological 

 activities. 



These experiments were performed in the 

 Biological Laboratory of the Brooklyn Insti- 

 tute of Arts and Sciences, Cold Spring Har- 

 bor, Long Island, July and August, and I am 

 vmder obligations to Dr. 0. B. Davenport, the 

 director of the laboratory, for the privileges 

 and opportunities so kindly extended. 



Hansford MacCurdy 



Alma College, 

 October 3, 1912 



