ARTIFICIAL PrRopucTION oF NoRMAL LARVe 543 
enzymes or other material. The ions and not the nucleins 
in the spermatozoon are essential to the process of fertiliza- 
tion (which may interest those who believe with me that 
physiologists ought to pay a little more attention to inorganic 
chemistry). I have no doubt that the same principles hold 
good for the process of fertilization of other, if not all, the 
marine animals, although the ions involved will probably 
differ in various species. 
Finally we may ask the question, whether we may expect 
to produce artificial parthenogenesis in mammalians. Jandsik 
has found segmentation in the unfertilized eggs of mam- 
malians. This is similar to the fact mentioned above, that 
the unfertilized eggs of sea-urchins may show a segmenta- 
tion if they stay long enough in the sea-water. I consider 
it possible that only the ions of the blood prevent the 
parthenogenetic origin of embryos in mammalians, and I 
think it further not impossible that a transitory change in 
the ions of the blood may also allow complete partheno- 
genesis in mammalians. 
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