270 LILLIE. [Vol. XVII. 



from an ^gg A B C D, then, according to the hypothesis, C 

 and D must reconstitute A and B before the typical develop- 

 ment can begin. But it can be shown that they are not recon- 

 stituted by growth ; and if complete reorganization of the areas 

 take place in the material of the part, their typical distribution 

 and proportions mnst be due to some prijnary mechanis7n of 

 the entire protoplasm independent of regional differentiation. 

 Finally, in the regeneration of Hydra, the fact that equal 

 parts from different regions form similar individuals shows 

 that the power of regeneration does not depend upon the 

 visible structural features, but on some underlying principle of 

 organization common to all parts of sufficient size. To argue, 

 therefore, for germinal localization from the facts of regenera- 

 tion is to miss the most characteristic feature in such regfen- 

 eration as that of Hydra, for the visible localization of parts 

 has no reference to the formative forces. 



Driesch has also been concerned with the problem of the con- 

 figuration of the protoplasmic mechanism in the tgg. In his 

 paper " Lokalisation morphogenetischer Vorgange " he form- 

 ally announces his discovery that the location of morphogenic 

 phenomena is a problem sni generis. After devoting a con- 

 siderable part of the introduction to the demonstration of this, 

 he begins Part I thus : " Having shown that the localization 

 of ontogenetic processes is a possible problem, we begin by 

 instancing a further example of this problem by recording the 

 results obtained on blastomeres of the echinoderm Qgg.'' Does 

 Driesch really believe that all the rest of the world has re- 

 mained in ignorance of the existence of such a problem .'' Is 

 he not aware that the theory of localized germ-areas is shaped 

 largely to the requirements of this problem .-' What does he 

 suppose that Loeb has in mind when he propounds the ques- 

 tion, "What are the circumstances which determine that only 

 one kind of organs originate at certain places in the body } " 

 (" On Some Facts and Principles of Physiological Morphology," 

 Biological Lectures, 1893, p. 38). It has long been generally 

 recognized that the morphological problems of any ontogenetic 

 process involve at least three factors : (i) its localization ; (2) the 

 time of its origin ; (3) its specific nature : (place, time, structure). 



