606 RALPH S. LILLIE 



was only slightly effective, while chloral hydrate showed well- 

 marked action. In all cases the anesthetic prevented or greatly 

 lessened the favorable effects of the after-treatment with hyper- 

 tonic sea-water. The results with sodium iodide were thus in 

 all respects similar to those with potassium thiocyanate. 



In table 5 I have summarized the results of last summer's series 

 of experiments with 0.55 m KCNS. The table includes the rec- 

 ords of all experiments in which the eggs were exposed, pre- 

 viously to treatment with the anesthetic-containing salt-solutions 

 to solutions of the same anesthetics in sea-water, in the manner 

 already described. ^^ ^j^g figures give the estimated proportion 

 of eggs remaining intact the next morning after the treatment 

 with the anesthetic-containing salt-solution alone. In all cases 

 the proportion of eggs surviving the treatment with the pure 

 0.55 m KCNS (without anesthetic) was small — never more than 

 1 or 2 per cent. 



The concentrations of anesthetic used in these experiments 

 are those which just suffice to prevent cleavage in most fertilized 

 eggs, without causing immediate injury.^^ The above solutions 

 (with the exception of 2.4 v. per cent propyl alcohol and 1.2 v. 

 per cent butyl alcohol, which are too strong) are thus," as regards 

 their inhibiting effect on cleavage approximately equivalent. 

 Nevertheless in their ability to prevent the cleavage-initiating 

 action of salt solutions they show marked inequalities. The alco- 

 hols are greatly superior to chloral hydrate and the urethanes; 

 amyl alcohol is distinctly more effective than the others, while butyl 

 alcohol appjears somewhat more favorable than propyl or capryl, 

 and ethyl is only moderately effective. This lack of parallelism 

 between the anesthetic and the above protective actions may 

 seem inconsistent with the general hypothesis advocated in this 

 paper. But when the essential dissimilarity between the process 

 of normal cleavage and the external action of a pure salt-solu- 

 tion is considered, the discrepancy ceases to be surprising. That 



'^ With the exception of a few experiments in which the results of fertilization 

 showed that the eggs were defective. 



1* Cf . my paper on the influence of anesthetics on cleavage cited above, pp. 128 



seq. 



