54 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



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. Experiments 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, calcium, 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 I 

 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 



