PAR THENOGENESIS 



Is therefore this: the egg-cell like many another living cell — 

 nerve or muscle, for example — possesses independent irri- 

 tability. It has full capacity for development. Neither 

 spermatozoa nor experimental means furnish the egg with 

 one or more substances without which the initiation of 

 development would be impossible. 



Here lay at the same time the possibilities and the failure 

 of the work on experimental parthenogenesis. Every 

 single investigator who erred in "proving" an external 

 agent (or agents) to be the cause of development neglected 

 an opportunity to extend our knowledge concerning that 

 fundamental manifestation of living matter, its independent 

 irritability. Some theories of fertilization derived from 

 work on experimental parthenogenesis postulated as the 

 cause of development a change in the egg, e.g., membrane 

 separation, that was however merely one consequence 

 of the ectoplasmic changes, or they related the cause of 

 development to some concomitant of mitosis. Others, as 

 had the Loeb theory, merely offered a substitute for the 

 sperm-borne centrosomes. Instead of these two structural 

 entities which Boveri had for some time postulated to be 

 indispensable for fertilization because he thought them to 

 be either lacking in the egg or present in too enfeebled state, ^ 

 the new school of biology substituted all kinds of means, 

 like lysins, mysticisms no less mystical because appearing 

 to belong to the realm of physical chemistry, having the 

 living condition of the spermatozoon always conveniently 

 at hand as a refuge finally to be sought.- 



I do not wish by seeming to dwell over long on this point 

 to take unfair advantage of the patent shortcomings of the 

 work on experimental parthenogenesis. And yet I must 

 hold it up as an example of what such a large section of the 



^ See also Fedjovsky, /SSS-p2. 

 - Loeb, ip/J. 



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