THE COMPARATIVE EFFICIENCY OF WEAK AND 



STRONG BASES IN ARTIFICIAL 



PARTHENOGENESIS 



JACQUES LOEB 



From The Rockefeller Institute for Medical Research, Neto York 



In 1905 the writer found that it is possible to induce artifi- 

 cial parthenogenesis (membrane formation) in the sea urchin 

 by weak acids, such as the monobasic fatty acids or CO2, but 

 not at all or only unsatisfactorily by the strong acids, such as 

 HCl, H2SO4, oxalic acid, and others. He suggested that this 

 paradoxical behavior was due to the fact that only those 

 acids which diffuse easily into the egg were able to cause 

 membrane formation.^ This assumption was supported by the 

 observation that there existed an analogy between the relative 

 physiological efficiency of various organic acids and their 

 corresponding alcohols. 



This paper intends to show that the weak base NH4OH 

 is much more efficient in the production of artificial partheno- 

 genesis than the strong bases NaOH, KOH, and tetraaethyl- 

 ammoniumhydroxide. The writer found in 1907 that it is 

 possible to substitute bases for acids in the process of artificial 

 parthenogenesis with this difference, that the eggs had to be 

 exposed to the alkaline solution for a considerably longer period 

 than to the acid solution in order to cause them to develop. - 

 The eggs of Strongylocentrotus could be caused to develop by 

 putting them for nearly three hours into a mixture of 50 cc. m/2 

 (NaCl + KCl + CaCU) + 0.5 or 1.0 cc. ^ NaOH. When such 



1 Loeb, Universit}^ of California Publications, vol. 2, p. 113, 1905. Also in 

 "Die chemische Entwicklungserregung des tierischen Eies," p. 100, Berlin, 1909. 



2 Loeb, Ueber die allgemeinen Methoden der kiinstlichen Parthenogenese, 

 Pfliiger's Archiv, Bd. 118, p. 572, 1907. 



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THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 13, NO. 4 



