580 JACQUES LOEB 



Only a small percentage of the eggs that had been in KOH 

 for forty-two minutes formed membranes and segmented, and 

 only a few of these developed into swimming larvae. 



e. Eggs sixty minutes in alkali. The eggs that had been in 

 NH4OH for sixty minutes formed membranes. Some began 

 to segment but the majority disintegrated without reaching 

 the larval stage. 



A considerable percentage of the eggs treated with KOH 

 for sixty minutes began to segment, but most of them disin- 

 tegrated before they reached the blastula stage. The rest of 

 the eggs remained intact. 



We may summarize the result of this experiment by saying 

 that practically all the eggs that had been treated with a 3/5000 N 

 solution of NHiOH for twenty-four minutes and were then put 

 into a neutral hypertonic solution for fifteen minutes developed 

 into larvae, this development being normal in a large number of 

 cases. The eggs, however, that were treated with a 3/5000 N solu- 

 tion of KOH for twenty-four minutes and then put into a neu- 

 tral hypertonic solution for fifteen minutes remained practically 

 unaltered. 



3. Comparison of the efficiency of NHiOH, NaOH and tetraaeth- 

 ylammoniumhydr oxide 



To three solutions of 50 cc. m/2 (NaCl + KCl + CaClo) were 

 added 0.3 cc.^ NH4OH, 0.3 cc. -^ NaOH, and 0.3 cc. ^ tetraaeth- 

 ylammoniumhydroxide respectively. Unfertihzed eggs of Arbacia 

 were put into these solutions for twenty-six minutes and were then 

 transferred directly into a neutral hypertonic solution, namely 

 50 cc. m/2 (NaCl + KCl + CaCl2) + 8 cc. 2^ m (NaCl + 

 KCl + CaCl2). They remained here for fifteen minutes and 

 were then transferred into normal sea water. 



Practically all the eggs that had been in 0.3 cc. NH4OH for 

 twenty-six minutes developed into larvae (about as quickly 

 as the larvae from fertihzed eggs) ; the eggs that had been in 0.3 

 cc. NaOH, or in 0.3 cc. tetraaethylammoniumhydroxide for 

 twenty-six minutes remained practically intact. Only a few 



