Artificial Parthenogenesis 127 



egg Into parts with and without a nucleus, — by dissection 

 or by shaking, is not sufficient to start development 

 in the sea-urchin egg. 



J. de Meyer put the spermatozoa of sea urchins 

 into sea water containing an extract of the eggs of the 

 same species but found only that the spermatozoa 

 swell in such a solution. Loeb and Bancroft made 

 extensive experiments in cultivating spermatozoa of 

 fowl in vitro on suitable culture media. In yolk and 

 white of egg the head of the spermatozoon underwent 

 transformation into a nucleus, but no mitosis or aster 

 formation was observed.^ These experiments should 

 be continued. 



* Loeb, J., Artificial Parthenogenesis and Fertilization, Chicago, 1913. 



