ACTIVATION OF STARFISH EGGS BY BUTYRIC ACID. 135 



are thus two ranges of temperature, one below 8, the other above 

 29, exposure to which may induce activation. Eggs may be 

 exposed to sea-water at 28 for 45 minutes without showing any 

 external signs of activation, such as membrane formation, al- 

 though some latent effect is probably produced. 1 At about 29 

 definite activation effects begin to appear, and at 30 these are 

 well marked. 2 It is found, however, that at temperatures con- 

 siderably below the range of heat-activation the action of 

 butyric acid is accelerated to a disproportionate degree by slight 

 rise of temperature; the temperature-coefficient of this action, at 

 first of the order 2-3.5, begins to show decided increase at 20 

 or even lower, and a rise from 26 to 28 approximately doubles 

 the rate of activation (see Table II). This behavior indicates 

 that at higher temperatures the combination of the acid is facili- 

 tated by some secondary change in the egg-system due directly 

 to the temperature. Apparently the structural conditions under 

 which the activating reaction proceeds are modified in a definite 

 manner by a rise in temperature. The indications are that at 

 30 and higher the structure is so altered that acids formed in the 

 egg itself (e. g., lactic) 3 become free to combine and cause acti- 

 vation; this hypothesis explains why heat-activation and acid- 

 activation exhibit so many features in common, in particular 

 closely similar relations between duration of exposure and degree 

 of activation. 4 The high temperature-coefficients of acid-activa- 

 tion above 20 are thus probably the expression of a super- 



1 This is indicated by the marked acceleration in the rate of acid-activation at 

 or near this temperature. See below, p. 142. 

 z Loc. cit., p. 268. 



3 This acid is formed rapidly in many cells at higher temperatures, as seen in the 

 phenomena of heat-rigor. 



4 Cf. my recent paper, BIOLOGICAL BULLETIN, loc. cit., p. 282: also Journ. Biol. 

 Chem., loc. cit., p. 234. 



Another characteristic effect which is produced in starfish eggs both by tem- 

 porary warming and by temporary exposure to butyric acid solutions is the pre- 

 vention of the maturation-process. Eggs exposed for some minutes to warm sea- 

 water (e.g., 32), within a few minutes after removal from the animals i.e., before 

 the dissolution of the germinal vesicle has begun remain permanently immature 

 (Journ. Exper. ZooL, 1908, Vol. 5, cf. p. 400). The same is true of eggs exposed 

 similarly to butyric acid solution. This identity in the physiological effect pro- 

 duced by the two apparently quite different treatments is a further indication that 

 these high temperatures act by causing the production of acid within the egg. 



