46 The Recapitulation Theory and Human Infancy 



changes up to the point in development when the new variation 

 appears, when, presumably, the hitherto unrelated "energies" 

 are suddenly connected up with the morphological sequence 

 of events. 



It has been clearly pointed out by the students of genetic 

 logic that in dealing with a genetic series of events the intel- 

 ligence works under constraints which do not hamper it in non- 

 genetic phenomena. A primary obligation laid upon thought 

 in such circumstances is that it shall deal fairly and accurately 

 with the phenomena of any one stage without reading into it 

 what the stage in question may ultimately lead to or what it 

 has proceeded from, except as evidences of these things are 

 actually exhibited in the phenomena. 75 



With these restrictions in mind we may recur to the facts 

 of development as they have been presented by the experi- 

 mental students of the subject. It is worthy of notice that 

 one of the many names applied to the experimental study of 

 development is Experimental Morphology, and it seems evi- 

 dent that in so far as the term "energies," in Cumings's usage, 

 is necessitated by the observed facts it is required in explan- 

 ation of morphological changes, minute and gross, that is, changes 

 of form. A primary dynamic expression, "induction," employ- 

 ed by Driesch, and by Jenkinson after him, is thus defined by 

 the latter: "An 'induction' is simply an effect produced upon 

 the parts that are developing by other parts, or possibly by some 

 factor in the external environment." 76 Perhaps, then, a juster 

 statement of the case would be that inasmuch as latent "en- 

 ergies' ' are known only as they express themselves in the struc- 

 ture and behavior of cells and their aggregates, resemblances 

 and differences in the latter will be the only available index 

 to the resemblances and differences of the "energies" which 

 lie within. Ontogenetic-phylogenetic resemblances, when they 

 have been truly described, therefore, must be regarded as real 

 and not factitious. Moreover, although it must be admitted 

 that the living substance has been greatly modified and differ- 

 entiated through descent, does it follow that it has been utterly 

 made over? If homologies do not refer to essential resemblances, 

 to what can they refer? 



77 See Dewey, Studies in Logical Theory, Ch. I; Baldwin, Development and Evolu- 

 tion, Ch. XIX. 



78 Experimental Embryology, 1909, p. 2. 



