PROLONGATION OF THE LIFE OF THE EGG 91 



Ten per cent of the eggs had been transformed into " shadows" 

 (white cytolysis). It goes without saying that all the eggs that 

 had been in the aerated hypertonic sea-water five and a half 

 hours were also dead. The eggs that had been in the same 

 solution in the absence of oxygen appeared all normal when 

 they were taken out of the solution, and three hours later- 

 the temperature was only 15 C. they were all, without excep- 

 tion, in a perfectly normal two- or four-cell stage. The further 

 development was also in most cases normal. They swam as 

 larvae at the surface of the vessel and went on the third day 

 (at the right time) into a perfectly normal pluteus stage, after 

 which their observation was discontinued. Of the eggs that 

 had been five and a half hours in the hypertonic sea-water 

 deprived of oxygen, about 90 per cent segmented. 1 



In another experiment newly fertilized eggs of purpuratus 

 were put into two dishes each containing 50 c.c. sea- water -f- 

 15 c.c. 2J m NaCl. To the one dish was added 1 c.c. 1/10 of 

 1 per cent KCN. The eggs remained 305 minutes in the solu- 

 tion. When they were put back into normal sea-water many of 

 those that had been in the dish containing KCN developed per- 

 fectly normally into plutei, while those that had been in the 

 solution without KCN all disintegrated into droplets in about 

 one-half hour. These experiments were often repeated and 

 they are indeed very striking demonstration experiments. They 

 show that the inhibition of oxidations in these experiments 

 protects the egg against the injurious effects of the hypertonic 

 solution for a considerable time. 



Chloral hydrate had also a very slight protective action. 

 When 2.5 c.c. N/10 chloral hydrate were added to 68 c.c. of the 

 hypertonic solution, about 5 per cent of the eggs were saved 

 under conditions under which KCN saved all the eggs. 2 



1 Loeb, University of California Publications, Physiology, III, 49, 1906. 



2 Loeb, "Ueber die Hemmung der toxischen Wirkung hypertonischer Losun- 

 gen auf das Seeigelei durch Sauerstoffmangel und Cyankalium," Pfluger's Archiv, 

 CXIII, 487, 1906. 



