THE PHYSIOLOGY OF CELL DIVISION 



39 



sea-water for thirty minutes usually caused considerable mem- 

 brane-formation and cleavage, and in a few cases gave a small 

 proportion of blastulae. Ether showed a similar though less 

 marked action; the proportion of eggs affected was in all cases 

 small. With cyanide, chloral hydrate, urethane, and chloretone 

 there was never any indication of membrane-formation or cleav- 

 age in eggs treated during the maturation period. Some shgnt 

 effect however was seen in eggs exposed in the later period, and 

 in three series a few eggs treated with chloretone, urethane, and 

 chloral hydrate formed larvae, though the great majority re- 

 mained unchanged. There was no action with cyanide. Appar- 

 ently the conditions of response to the membrane-forming treat- 

 ment undergo a certain change after maturation is complete: 

 the increased resistance to normal fertilization then appearing is 

 associated with a change in the effects produced by the -above so- 

 lutions of anesthetics. The existence of a certain proportion of 

 eggs showing a behavior more or less divergent from the norm 



TABLE 5 

 June 25, 1912: Unfertilized starfish eggs of the same lot were placed in the following 

 solutions at two different intervals after removal from the animals; part A about 

 one-and-a-quarter hours after removal, part B about two hours later. After remain- 

 ing in the solutions for thirty minutes they were returned to sea-water. The. con- 

 dition of the eggs next day was as folloivs: 



A (exposed IJ H. AFTER 



removal) 



B (exposed 3| h. after 

 removal) 



2. m/lOOOKCN. 



1. Hypertonic sea-water. About half the eggs show 

 membrane-formation; the 

 rest have coagulated un- 

 changed. ^ No blastu- 

 lae 

 No effect. All coagulated 

 unchanged 



3. 0.6 V. % ether i Almost all coagulated un-i 



changed. A few mem-| 

 branes 

 All coagulated unchanged 

 All coagulated unchanged i 



4. 0.1 % chloral hydrate 



o. 0.2 % urethane 



6. l/lO saturated chlorC' 

 tone All coagulated unchanged 



Majority coagulated un- 

 changed; no blastulae 



All coagulated unchanged 



Great majority coagulated 

 unchanged; a few blas- 

 tulae present 

 All coagulated unchanged 

 All coagulated unchanged 



All coagulated unchanged 



1 That is, show the same condition as the untreated control eggs — dead and 

 coagulated without membrane-formation or cleavage. 



