Artificial parthenogenesis and fertilization / by Jacques Loeb... Originally tr. from the German by W. O. Redman King... supplemented and revised by the author.

  • Loeb, Jacques, 1859-1924.
Date:
[1913]
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Licence: In copyright

Credit: Artificial parthenogenesis and fertilization / by Jacques Loeb... Originally tr. from the German by W. O. Redman King... supplemented and revised by the author. Source: Wellcome Collection.

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    experiments through which it is possible to cause, by Chemical means, the unfertilized eggs of various animals to develop into larvae. Such a study could not be undertaken without applying the methods of experimental and, more especially, quantitative research. As long as the Spermatozoon was the only means of calling forth the development of the egg it was impossible to undertake a physicochemical analysis of this process. The Work on artificial parthenogenesis, i.e., the Substitution of well- known physicochemical forces for the Spermatozoon, made such an analysis possible. The older so-called theories of fertilization were merely metaphors. The egg was compared to a clock, and it was said that the Spermatozoon set this clock in motion. Others said that the Spermatozoon communicated to the egg a pecu- liar mode of Vibration, and still others maintained that the Spermatozoon imparted a “Stimulus” to the egg. “Stimulus” is a technical term, but scientific problems are not solved by mere acts of nomenclature or rhetoric. With the rise of cytology more definite ideas in regard to the mechanism of fertilization were expressed. 0. Hertwig defined fertilization as the fusion of the sperm nucleus with the egg nucleus. While this fusion has a bearing upon the transmission of the paternal characters to the offspring, it does not give us any insight into the nature of the forces by which the egg is caused to develop. Hertwig’s definition is also incorrect, as was clearly demonstrated by Boveri who found that the fusion of the egg and sperm nucleus had nothing at all to do with the causation of the development of the egg. For he was able to show that an egg deprived of its nucleus can actually develop into an embryo if a Spermatozoon enters it. In this case no union of two nuclei takes place. Boveri replaced Hertwig’s definition by a hypothesis that was more in accordance with the facts. According to him, the