2. ANALYTICAL THEORY OF MORPHOGENESIS l 



a. THE DISTRIBUTION OF MORPHOGENETIC POTENCIES 



Prospective Value and Prospective Potency 



Wilhelm Eoux did not fail to see that the questions of 

 the locality and the time of all morphogenetic differentia- 

 tions had to be solved first, before any problem of causality 

 proper could be attacked. From this point of view lie 

 carried out his fundamental experiments. 



It is only in terminology that we differ from his views, if 

 we prefer to call our introductory chapter an analysis of 

 the distribution of morphogenetic potencies. The result 

 will be of course rather different from what Eoux expected 

 it would be. 



Let us begin by laying down two fundamental concepts. 

 Suppose we have here a definite embryo in a definite state 

 of development, say a blastula, or a gastrula, or some sort of 

 larva, then we are entitled to study any special element of 

 any special elementary organ of this germ with respect to 

 what is actually to develop out of this very element in the 



1 Compare my Analytische Theorie der organischen Entwickelung, Leipzig, 

 1894, and my reviews in Ergebnisse der Anatomic und Entwickelungsges- 

 chichtc, vols. viii. xi. xiv. , 1899-1905. A shorter review is given in 

 Ergebnisse der Physiologie, vol. v., 1906. The full literature will be found 



in these reviews. 



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