140 Mr. E. Whitley. Effect of Acid, etc., on [Nov. 14, 



tumblers, to show any changes in reaction that might take place during 

 growth. When it was observed that they had a specific action upon the 

 eggs, a series of experiments was undertaken with them, the results of which 

 are shown in Tables VII — X. In all the experiments, except those recorded 

 in Table X, two drops of the indicator were added to 200 c.c. of sea-water, or 

 sea- water plus varying quantities of alkali, in a tumbler. Table X records 

 the results of varying the amount of phenol-phthalein employed. It will be 

 seen that, although the indicators were made up in alcoholic solution, the 

 amount of alcohol added in each case to 200 c.c. of liquid, was quite 

 insufficient to materially influence the result. 



The experiments without indicators, recorded in Tables VIII and IX, 

 are included for purposes of comparison. 



It will be observed from the figures obtained that dimethyl is very 

 deadly to the eggs of Pleuronectes and phenol-phthalein innocuous, while the 

 opposite holds good with Echinus, the dimethyl having, if anything, a 

 favouring effect on growth, and the phenol-phthalein being very injurious. 

 Before killing, phenol-phthalein appears to be very effective in producing 

 irregular divisions. The dimethyl was readily absorbed as such by both 

 the organisms, staining them a deep yellow, so there can be no question 

 as to its having thoroughly penetrated the tissues. 



So far as can be ascertained, this specific action of indicators has not been 

 noted before, and no explanation can be given of the fact of the different 

 indicators affecting the two organisms in exactly opposite ways. Tadpoles in 

 tap-water, to which the same, and even much larger amounts of these 

 indicators had been added, appeared to be totally unaffected by either. 



It might be of interest to repeat the experiments with other organisms, 

 and with other organic compounds not known already to act as poisons. 



Summary. 



(1) The amount of variation from the normal concentration of hydrogen 

 and hydroxyl ions in sea-water which the eggs of Pleuronectes will tolerate 

 is very small. 



(2) A disturbance of the equilibrium towards the acid side is much more 

 fatal than the opposite. 



(3) A progressive development of resistance to an unfavourable action of 

 the environment takes place in proportion to the age of the eggs. 



(4) Phenol-phthalein is deadly to the eggs of Echinus esculentus, but 

 harmless to those of Pleuronectes, while dimethyl quickly kills the latter, 

 and appears, if anything, to have a favourable influence upon the develop- 

 ment of the former. 



