28 PROBLEMS OF FERTILIZATION 



operate at the various linkages of such a reaction. In 

 its reaction with the sperm the fertilizin of different 

 species exhibits a certain degree of specificity, which 

 should be more fully studied, but which has been partly 

 explored by Jacques Loeb and myself. 



This form of hypothesis takes into account the inter- 

 nal factors both of maturity of germ cells and of their 

 specificity; it is also adapted to explain the environ- 

 mental conditions of fertilization extremely well; and 

 it is consistent with the results of parthenogenesis, and 

 the known relations of parthenogenesis and fertilization 

 to the permeable or impermeable conditions of the egg 

 membrane. 



In the following pages we shall discuss the various 

 problems whose history has thus been outlined. The 

 discussion can be no more than a record of progress. 



REFERENCES 



AuERBACH, Leopold. 



1874. Organologische Studien (see pp. 1^^-262). Breslau. 



BlSCHOFF, T. L. W. 



1842. Entwickelungsgeschichte des Kaninchens (chap. ii). 

 1847. "Theorie der Befruchtung und liber die Rolle, welche 



die Spermatozoiden dabei spielen," Arch, fiir Anat. 



u. Phys., pp. 422-42. 



B OVERT, T. 



1887. "Ueber die Befruchtung der Eier von Ascaris megalo- 

 cephala," Sitzimgsher. d. Gesell. fiir Morph. u. Phys. 

 (Miinchen), Band 3, pp. 71-80. 



1887. "Ueber den Antheil des Spermatozoons an der 

 Theilung des Eies," ibid., pp. 154-64. 



1887. "Zellenstudien," Heft I, Jen. Zeitschr. fur Naturw., 

 Band 21, pp. 423-51 S- 



1888. "ZeUenstudien," Heft II, ibid., Ba.nd 22, pp. 685-882. 



