EFFECT OF EXTRACTS UPON DEVELOPING EGGS. 89 



Series 63. 



In the table below are given some observations made in sea 

 water whose OH concentration had been raised by the addition 

 of 0.8 c.c. N/io NaOH to 50 c.c. sea water. This experiment 

 was also designed as a check upon the experiments in which nor- 

 mal sea water was used. Loeb ('98) brought out the fact that 

 by allowing eggs, fertilized normally, to develop up to the blastula 

 stage, and then dividing the eggs into three lots, to one of which 

 NaOH is added in the proportion of 1.76 c.c. N/io NaOH to 

 100 c.c. of sea water, a second to which the same amount of 

 N/io HC1 is added, and the third for the control, at a given time 

 the bowl containing NaOH shows complete plutei, the HC1 culture 

 shows late gastrulse with a few short-armed plutei, while the 

 control contains many plutei in various stages, and some late 

 gastrulce. In the report of this experiment Loeb attributed this 

 result to an increased rate of oxidation produced by the OH-ion. 17 

 Now, on this hypothesis, if the retardation in the development of 

 the eggs due to the presence of the egg extract is a slowing down 

 of the oxidation rate, then presumably the NaOH should neutral- 

 ize, or antagonize this effect, and we should expect a rate of 

 development more nearly normal. 



The experiments proved that just the reverse is true, however, 

 for the effect of the NaOH was not to neutralize, but rather to 

 add to the effect of the extract, since it can be seen by glancing at 

 the table that, if anything, in the culture containing NaOH plus 

 extract, there was a slight retardation in the early cleavage rates 

 compared with the NaOH control. A more marked degree of 

 retardation was shown in the development from the blastula to 

 the pluteus. 



This result is in entire agreement with the later work of 

 Loeb. 18 In his book he says that although the rate of develop- 

 ment of Arbacia can be retarded by the addition of acids to the 

 sea water, he has not succeeded in showing that the rate of de- 

 velopment in Arbacia eggs can be accelerated by the use of 

 hydroxyl-ions in the sea water. Glaser found that this latter 



!" Glaser, Otto, " Qual. Analysis of Egg Secretions and Extracts of Arbacia 

 and Asterias." BIOL. BULL., Vol. XXVI., No. 6, June, 1914. 



is Loeb, Jacques, " Artificial Parthenogenesis and Fertilization," Chicago, 

 1913. 



