ABSTRACT
Unfertilized sea-urchin eggs produce acid when they are cytolysed or fertilized (Ashbel,, 1929; Runnstr öm, 1933 a, 1935). Neither the post-fertilization nor the post-cytolysis acid has been identified. The number of different acids which might be released is large, and it has not so far been considered expedient to attempt direct analysis of the sea water surrounding the activated eggs. One way of establishing the nature of the acid is by observing the effect of specific metabolic inhibitors on its production. Runnström (1933 b, 1935) used this technique, but the inhibitors used were all negative in their effect, i.e. they did not inhibit acid production. Runnströom investigated the effect of inhibitors which affect one type of glycolysis.1 This paper is also concerned with the effect of a glycogen breakdown inhibitor. If the acid production after cytolysis is associated with the formation of hexose phosphate from glycogen, it should be partly or wholly inhibited in the presence of phlorizin (Lundsgaard, 1933).
This paper is not concerned with carbohydrate breakdown without phosphorylation (Bumm & Fehrenbach, 1931).
This effect was firat noticed in Echinus esculentus eggs by Gray (unpublished), to whom I am indebted for suggesting a further investigation of the effect.
The radius of unfertilized E. esculentus eggs was 82.6 ± 4.2µ (S.E. of mean).
The whole of this analysis depends on the amount of saponin tipped in being sufficient completely to cytolyse all eggs in the manometer vessels. If this precaution is not taken the results become exceedingly difficult to analyse.
Tyler and Schultz’s (1932) experiments on the eggs of Urechis caupo and the more recent experiments of Tyler (1937) on various marine eggs may indicate that activation is partially reversible.
The results described in this paper have very recently been repeated using the more accurate Warburg differential method (1924).
Runnström (19336) showed that the cell membrane of Arbacia eggs is permeable to iodoacetate. Ellis (1933) also considers that iodo-acetate has no effect on fertilization or division, but penetrates the fertilized eggs, as evidenced by decreased glutathione content in fertilized eggs treated with iodo-acetate.
