236 THE PHYSIOLOGY OF REPRODUCTION ' 



Loeb's conclusion was that the phenomenon of fertilisation (as 

 studied in the sea-urchin, the starfish, Lottia, Polyiwe, and Sipunculids) 

 consisted essentially, firstly, in a liquefaction or hydrolysis (or both) 

 of certain fatty compounds in the ovum, and secondly, in an initiation 

 in the right direction of a new process of oxidation.^ These changes 

 which occur in the fertilised egg lead to the synthesis of nuclein 

 material from the protoplasm. According to this view, the process 

 of astrosphere formation is not the direct effect of the act of 

 fertilisation, but is a secondary consequence of the new chemical 

 changes which are brought about by the entrance of the sperma- 

 tozoon. 



In a later work Loeb ^ has elaborated his theory further. Mem- 

 brane formation is regarded as an essential factor in normal 

 fertilisation, and is, of the nature of a cytolysis of the egg, for all 

 cytolytic agents {e.g. foreign blood or cell extracts) produce it. 

 Normally the fertilisation membrane is brought about by a lysin 

 carried in by the spe^-m, which also carries another substance that 

 serves to counteract the evil effects of membrane formation (p. 194). 



Delage,^ however, has adduced experimental evidence, some of 



tingen liber den Einfluss der Befruchtung und der Zahl der Zellkerne auf 

 die Sauiebildung im Ei," Biochem. Zeitsch., vol. ii., 1906 ; " tJber. die Super- 

 position von ktinstlichen Parthenogenese und Samenbefruchtung in demselben 

 Ei," Arch. f. Entwich.-Mechanik, vol. xxiii., 1907; "tJber die allgemeinen 

 Methoden der ktinstlichen Parthenogenese," Pfliiger's Arch., vol. cxviii., 1907 ; 

 and other papers in the same volume. The following papers also deal, with 

 artificial parthenogenesis in various animals : Delage, C R. de VAcad. des 

 Sciences, vol. cxxxv., 1902 (describing fertilisation by anaesthetisation with 

 carbon dioxide during maturation) ; and G. R. de t'Acad. des Sciences, vol. cxli., 

 1906 (describing fertilisation with various salt solutions) ; Treadwell, " Notes 

 on the Nature of Artificial Parthenogenesis in the Egg of Patella obscura," 

 Biol. Bull., vol. iii., 1902 ; Scott, " Morphology of the Parthenogenetic 

 Development of Amphitrite," Jour, of Exper. Zool., vol. iii., 1906 ; Lefevre, 

 " Artificial Parthenogenesis in Thalassema mellita," Jour, of Exper. Zool., 

 vol. iv., 1907 ; Kostanecki, " Zur Morphologie der ktinstlichen partheno- 

 genetischen Entwicklung bei Mactra," Arch. f. Mikr. Anat., vol. Ixxii., 1908. 

 See also Mathews, whose paper has been already referred to (Chapter IV., 

 p. 129, " A Contribution to the Chemistry of Cell Division, Maturation, and 

 Fertilisation," Ainer. Jow: of Pkydol., vol. xviii., 1907). This author lays stress 

 on the part played by the centriole, and suggests " that the various methods 

 employed to produce artificial parthenogenesis do not do so by their direct 

 physical action on the cell, but indirectly by producing in one way or another 

 active centriole substance in the cell cytoplasm, or by causing its discharge 

 from the nucleus." 



1 Loeb, "The Chemical Character of the Process of Fertilisation and its- 

 bearing upon the Theory of Life Phenomena."— Address before, the Inter- 

 national Congress of Zoologists, Boston, 1907, Univ. of California Publications, 

 vol. iii., 1907. 



2 Loeb, Die chemische Entwickhmgserregung des tierischen Eies, Berlin, 1909 ; 

 Artificial Parthenogenesis and Fertilisation, Chicago, 1913 ; and Lillie, Prohlerm 

 Atf fertilisation, Chicago, 1919. These important works contain full references. 

 For further discussion of the subject see p. 313 See also pp. 185 and 194. 



3 Delage, "Les Vrais Facteurs de la Parth6nog6nfese Exp6rimentale," v 

 Arch, de Zool. Expdr. et Oen., vol. vii., 1908. 



