150 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



of this statement has been furnished by eggs stained red with 

 neutral red. Warburg has shown that if a small amount of 

 NH 4 OH is added to the solution the eggs turn yellow, while 

 when NaOH is added they remain red. 1 Harvey has shown that 

 not only the egg cells but cells in general behave this way, 

 and that the cells are impermeable for all strong bases (NaOH, 

 KOH, tetraethylammoniumhydroxide) while they are perme- 

 able for weak bases like NH 4 OH or the amines. 2 The bases 

 as well as the acids must be able to diffuse into the egg in order 

 to cause artificial parthenogenesis. 3 



3. When a trace of KCN is added to the alkaline solution 

 its effect is diminished and the eggs must either remain longer 

 in the alkaline solution or longer in the hypertonic solution 

 in order to produce larvae. In former experiments on the 

 unfertilized eggs of Strongylocentrotus the writer could show that 

 the parthenogenetic effects (as well as the destructive effects) of 

 NaOH can be inhibited if the solution is deprived of oxygen. 4 



4. If the eggs of Arbacia are treated with alkali alone, 

 without being afterward submitted to a treatment with a hyper- 

 tonic solution, they may form fine gelatinous surface films (mem- 

 branes) and begin to develop, but they will then disintegrate. 



To 50 c.c. m/2 (NaCl+KCl+CaCl 2 ) were added 0.3 c.c. 

 N/10 NH 4 OH, 0.3 c.c. N/10 NaOH, and 0.3 c.c. N/10 tetra- 

 ethylammoniumhydroxide respectively. Unfertilized eggs of 

 Arbacia were put into these three solutions for forty-two min- 

 utes and then transferred to normal sea-water. All of the eggs 

 that had been in the solution containing the NH 4 OH segmented 

 in a rather amoeboid way into two or four cells, after which the 

 cells fell apart and disintegrated. All of the eggs that had 



1 Warburg, Zeitschr. f. physiol. Chem., LXVI, 305, 1910. 

 - Harvey, Jour. Exper. Zool., X, 507, 1911. 



3 Loeb, op. cit. 



4 Loeb, "Weitere Versuche ueber die Notwendigkeit von freiem Sauerstoff 

 fiir die entwicklungserregende Wirkung hypertonischer Losungen," Pfluger's 

 Archiv, CXVIII, 30, 1907. 



