1905.] Effects of Alkalies, etc., on Eggs of Echinus. 103 



onward the rate of growth and any irregularities in cell division can be 

 observed, and the effects of the addition of alkali or acid, or alkaline or acid 

 salt, can be compared under exactly similar conditions, and contrasted with 

 a control grown alongside in unaltered sea-water. 



The experiments were made, by kind permission of Professor W. A. 

 Herdman, B.B.S., at the Marine Biological Station, Port Erin, Isle of Man, 

 during the month of April, 1905. 



J. Loeb,* in 1898, reported experiments on the influence of acids and 

 alkalies on the development of the larvse of sea-urchins, showing that the 

 addition of acids to the sea-water delayed the development, and finally, at a 

 certain concentration of hydrogen ions, inhibited the development com- 

 pletely. With the addition of alkalies the development during the first 

 12 hours was not at all hastened, or hastened to a hardly appreciable extent. 

 On the second day, however, and sometimes also even on the third day, 

 the eggs that developed in sea-water which had been made alkaline were 

 occasionally, but not always, in advance of eggs of the same brood which had 

 been raised in normal sea- water. 



At the time of the publication of this paper, Loeb held the current view 

 that sea- water had an alkaline reaction, and accordingly drew the conclusion 

 that, for developmental processes, it is necessary to have an alkaline reaction 

 or, in other words, a higher concentration of hydroxyl ions than exists in 

 distilled water. 



At a later date Loeb.f however, came to the conclusion that normal sea- 

 water must be regarded as a practically neutral solution, and hence ascribed 

 the favouring action of alkalies upon cell-division and growth to the 

 neutralizing action of the alkali added upon acid products formed by the cells 

 in the process of growth which would otherwise cause an accumulation of 

 hydrogen ions and arrest the development. 



This opinion is based by Loeb upon the results of the observations of 

 PriedenthalJ PraenkeLJ and Parkas,|| which indicate that blood-plasma 

 possesses no higher concentration in hydroxyl ions than distilled water ; upon 

 observations made by Dr. Cottrell at Loeb's suggestion upon the sea-water of 

 the Bay of San Francisco by means of hydrogen electrodes, which showed 



* 1 Arch. f. Entwickelungsmechanik d. Organismen,' 1898, vol. 7, p. 631. 



t 1 Arch. f. d. ges. Physiol.,' 1903, vol. 99, p. 637 ; ibid., 1904, vol. 101, p. 340 ; ibid., 

 1904, vol. 103, p. 506 ; ' Univ. of California Publications, Physiology,' 1903—4, vol. 1, 

 pp. 39, 139. 



+ 'Arch. f. Anat. u. Physiol., PhysioL Abth.,' 1903, p. 550. 

 § ' Ax2h. f. d. ges. Physiol.,' vol. 96, 1903, p. 601. 



|| ' Arch. f. d. ges. Physiol.,' vol. 98, 1903, p. 551 ; see also Hober, ' Arch. f. d. ges. 

 Physiol.,' vol. 99, 1903, p. 572. 



I 2 



