54 ARTIFICIAL PARTHENOGENESIS AND F ERTILIZATION 
statement that the effect of the hypertonic solutions upon the 
egg consisted in the production of artificial astrospheres and 
centrosomes, and that such astrospheres and centrosomes were 
the organs of cell division. He considered that a development 
of unfertilized eggs treated with hypertonic sea-water to larvae 
was quite excluded. 
Meanwhile I had been led by the results of my investiga- 
tions upon the effects of ions to the question whether it might 
not be possible to cause unfertilized eggs to develop into larvae 
by treating them with modified sea-water. Ixxperiments upon 
the physiological effect of the galvanic current had led me to 
the conclusion that in such cases we are dealing with an ion 
effect—an idea which was new at that time but which is con- 
sidered a matter of fact today—and since the galvanic current 
is a sovereign method of stimulating muscle and nerve, it gave 
me the idea that perhaps ion effects might really underlie the 
action of all stimuli which had not hitherto been closely ana- 
lyzed. Ringer’s and my own experiments with certain salts 
showed that solutions of sodium, lithium, caletum, and rubidium 
salts could send skeletal muscles into rhythmic or at least 
fibrillar contractions, while salts of calcium, magnesium, and 
strontium prevented these contractions. Hence we owe it 
to the presence of the calcium salts or ions in our blood that 
our muscles do not continually contract. 
Now as mentioned above, it had been made known by Hert- 
wig and others, and I myself had often enough observed in 
Arbacia, that the unfertilized eggs of certain animals occasion- 
ally begin to divide provided they remain long enough in sea- 
water. This suggested that the unfertilized egg might be in 
just the same condition as the muscle in that the egg could 
develop without fertilization, but that something contained 
in the sea-water prevents its development, just as the Ca 
and Mg contained in the blood prevent fibrillar contractions 
of the muscles. Hence I decided to perform experiments in 
