VII 



ON THE NATURE OF FORMATIVE STIMULATION 

 (ARTIFICIAL PARTHENOGENESIS)! 



PREFACE 



The title of this paper was chosen in reference to Virchow's 

 paper on "Stimulation and Irritability" (Virchow's Archiv, 

 XIV, 1, 1858) in which he discriminates between three forms of 

 stimulation : functional, nutritive, and formative. By formative 

 stimuli he means those which give rise to nuclear and cellular 

 division. He considers as the classic example for formative 

 stimulation the fertilization of the egg and the parallel drawn 

 by him between this process and the causation of a pathological 

 process of growth is so characteristic that we may quote it in full : 



If we admit the identity between the pathological and the embry- 

 onic neoformation, the egg will have to be considered as the analogue 

 of the pathological mother cell and the act of impregnation as the 

 analogue of pathological stimulation. This view is not essentially 

 altered through the discovery of the entrance of the spermatozoon 

 into the egg, since there is no reason to consider the spermatozoon as 

 the direct morphological starting-point for the development of definite 

 parts of the egg. If, as seems to be the case, the spermatozoa are 

 dissolved in the egg, they carry into it only certain chemical substances, 

 which serve as specific stimuli, by calling forth new chemical and 

 morphological arrangements of the atoms. Each specific contagium 

 offers the same possibiUties. 



The supposition prevalent at Virchow's time, that the 

 spermatozoon is entirely dissolved in the egg was not correct; 

 but his view, that the spermatozoon carries chemical substances 

 into the egg, which form the stimulus for its development, is 

 perfectly correct; and likewise the analogy between the causa- 

 tion of the development of the egg by a spermatozoon and the 

 causation of a pathological growth seems correct. I therefore 



1 Address delivered at the International Medical Congress at Budapest, 1909. 



127 



