ARTinCIAL PAETHENOGENESIS AND FERTILISATION. 505 



enzyme solutions. His results were wholly negative, and he 

 concluded that, used in certain proportions and under certain 

 conditions at any rate, such extracts did not possess any 

 power of causing proliferation of the ripe ovum. No 

 evidence could be furnished of the existence of a zymogen 

 in spermatozoa. Extracts of fertilised eggs in the earlier 

 stages of development seemed likewise devoid of any seg- 

 mental activity. The results, Gies adds, do not, however, 

 certainly show that enzyme action is impossible, after, or at 

 the time of union of the spermatozoon with the ovum, within 

 the latter. 



The same negative result was got this spring by R. T. 

 Lieper at Millport Marine Biological Station, using an 

 extract of sperm prepared by spreading fresh sperm on 

 sheets of glass, then drying in air and sun, and afterwards 

 triturating the dried extract in sterilised sea water. The 

 filtrate from this fluid produced no segmentations, though 

 control experiments with eggs from the same ovaries 

 normally fertilised, nearly all developed. 



Literature. 



AiuoLA. — ' AUi Soc. Ligrest. Sc. Nat. e Geogn.,' ami. xii, fasc. 3. 

 Bataillon, 1900. — 'Comi)t. Rendus de I'Acad. des Sciences,' t. cxxxi, p. 115 

 Bataillon, 1901. — 'Compt. Uendus de I'Acad. des Sciences,' t. cxxxii, pp 



852, 1134. 

 Bataillon, 1902. — ' Coiiipt. Rendus de I'Acad. des Sciences,' t. cxxxiv, p. 918 

 Bataillon. — ' Arcliiv fiir Entwicicelungsmeclianik,' t. xi, Heft 1. 

 Bataillon. — 'Arcliiv I'iir Entwickelungsniechanik,' t. xii. Heft, 4. 

 Bonnet, 1900. — Mcrkel iind Boniiet-Ergebnisse u. s. w.,' 1900. 



BovERi, 1888. — ' Sifzungsber. des Ges. f. Morjili. und Phvsiol. in Miinclicn, 

 Bd. iv, Heft 2. 



BovERi, 1901.—' Zellen Siudien,' Heft 4, Jena, 1901. 

 BovERi, 1902.—' Das Problem der Befruclitung,' Jena, 1902. 

 Bryce, 1902. — 'Quart. Journ. Micr. Sci.,' vol.-xlvi. 

 BuLLER, A. R., 1902. — ' Quart. Journ. Micr. Sci.,' vol. xlvi. 



