FERTILIZATION' 175 



ingly without segmenting. Frank Lillie* afterward examined such 

 eggs histologically and convinced himself indeed that such is the case. 

 Bullotf produced a much more normal type of development in the un- 

 fertilized eggs of another Annelid, Ophelia, by submitting these eggs 

 for about two hours to hypertonic sea water. In this case the segmen- 

 tation was normal and the larvae formed were also normal, but they 

 only lived two days. It will therefore be of interest to find out whether 

 in ChcBtopterus the same means which in Echinoderms lead to a mem- 

 brane formation are able to induce a parthenogenetic development 

 which resembles in all its features the development caused by a 

 spermatozoon. 



Kostanecki | found that by a treatment with hypertonic sea water, 

 the unfertilized eggs of a Mollusk (Mactra} could be caused to undergo 

 the first segmentations; and I found afterward that this method led 

 in other Mollusks (Lotlia, Acnma) to the production of swimming larvae. 

 I have recently tried my new method on the eggs of Lottia gigantea. 

 It seems that the combination of the treatment with fatty acid and 

 hypertonic sea water gives better results than the osmotic treatment 

 alone. Some attempts have been made to cause the eggs of vertebrates 

 to develop parthenogenetically. Bataillon|| has shown that the unfer- 

 tilized eggs of the frog and of Petromyzon can be caused to segment as 

 far as the morula stage by putting them for some time into a salt solu- 

 tion of a certain concentration, whereby they lose water. 



It was natural to try whether or not substances can be extracted 

 from the spermatozoon which cause the unfertilized egg to develop. 

 Fieri made the statement that this could be done, but he evidently worked 

 with sea water contaminated by spermatozoa. After the appearance 

 of my first paper, H. Winkler made experiments with the extract of 

 spermatozoa of sea urchins which, according to his description, caused 

 the eggs of the same species to go through the first stages of segmenta- 

 tion; If no larvae, however, developed from these eggs. These experi- 

 ments were repeated by Gies, who tried to ascertain whether or not an 

 enzyme could be obtained from the spermatozoon which caused the 

 unfertilized egg to develop; but the results were absolutely negative. 

 Not a trace of segmentation could be produced in eggs treated with such 

 extracts. These results contradict the conclusions of Winkler.** I am 

 inclined to believe that Winkler worked with sea water whose concen- 



* F. Lillie, Archiv fur Entwickelungsniechanik, Vol. 14, p. 477, 1902. 



t Bullot, Archiv fur Entwickelungsniechanik, Vol. 18, p. 161, 1904. 



J Kostanecki, Bulle. Academie de Sciences, Krakau, 1902. 



Loeb, University of California Publications, Physiology, Vol. I, p. 7, 1903. 



|| Bataillon, Archiv fitr Entwickelungsniechanik, Vol. 18, 1904. 



If Hans Winkler, Nachrichten der Gesellsch. der IVissenschaften zu Gottingen, p. 87, 1900. 



** Gies, Am. Jour, Physiology, Vol. 6, p. 53, 1901. 



