596 RALPH S. LILLIE 



Experiments ivith potassium thiocyanate 



Table 1 summarizes the results of two typical series of experi- 

 ments. These illustrate in a typical manner the characteristic 

 effects of magnesium and calcium in preventing the cleavage- 

 initiating action of the alkali salt; the four alcohols also show a 

 well-marked though less pronounced antagonistic action. The 

 superiority of amyl alcohol and the relative ineffectiveness of 

 ethyl urethane are also typical. 



It will be noted that the degree of antagonism is decidedly 

 greater in the case of those eggs (Series B) that were anesthe- 

 tized previously to the treatment with the salt-solutions. This 

 effect had been foreseen; presumably the preliminary anesthe- 

 tization alters the plasma-membranes of these eggs, which are 

 thus already in a relatively resistant condition when brought 

 into the salt-solutions; hence the action of the latter on these 

 eggs is more gradual than on eggs transferred to the solutions 

 directly from normal sea-water. In the latter case it is to be 

 assumed that the salt begins to exert its action before the anes- 

 thetic has had time to produce its full effect. There is a similar 

 difference in the action of anesthetic-containing sodium chloride 

 solutions on normal and on anesthetized Arenicola larvae.^ Sev- 

 eral other similar experiments gave the same general result. 



The further fact appears clearly from these experiments that 

 the anesthetics are less efficient than calcium and magnesium in 

 counteracting the action of the alkali salt. A considerable and 

 variable proportion of the anesthetic-treated eggs form fertili- 

 zation-membranes and cleave, and later break down like eggs 

 treated with the pure anesthetic-free salt-solution. The pro- 

 portion of protected and intact eggs may, however, reach 80 or 

 90 per cent with a favorable anesthetic like amyl alcohol; such 

 eggs appear quite normal and remain without change for many 

 hours; if fertilized they develop into swimming larvae. 



The physiological condition of these eggs is, however, not the 

 same as that of normal eggs, but has been altered, apparently 

 in the same general direction as in those eggs which form definite 



9 Cf. Am. Jour. Physiol., 1912, vol. 29, p. 384. 



