78 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



As the most important special morphogenetic case is, of 

 course, the so-called " normal " one, we can also express our 

 formula in terms of special reference to it : there are more 

 morphogenetic possibilities in each part than the observation 

 of the normal development can reveal. Thus we have at 

 once justified the application of analytical experiment to 

 morphogenesis, and have stated its most important results. 



As the introductory experiments about " Entwickelungs- 

 mechanik " have shown already that the prospective potency 

 of embryonic parts, at least in certain cases, can exceed 

 their prospective value that, at least in certain cases, it can 

 be different from it the concept of prospective potency at 

 the very beginning of our studies puts itself in the centre of 

 analytical interest, leaving to the concept of prospective 

 value the second place only. For that each embryonic part 

 actually has a certain prospective value, a specified actual 

 fate in every single case of ontogeny, is clear from itself and 

 does not affirm more than the reality of morphogenetic cases 

 in general ; but that the prospective value of the elements 

 may change, that there is a morphogenetic power in them, 

 which contains more than actuality ; in other words, that 

 the term " prospective potency " has not only a logical but a 

 factual interest : all these points amount to a statement not 

 only of the most fundamental introductory results but also 

 of the actual problems of the physiology of form. 



If at each point of the germ something else can be formed 

 than actually is formed, why then does there happen in each 

 case just what happens and nothing else ? In these words 

 indeed we may state the chief problem of our science, at least 

 after the fundamental relation of the superiority of prospec- 

 tive potency to prospective value has been generally shown. 



