318 EEV. J. T. GULICK OX 



old age and disease in the individual. These and other parallel 

 laws in the growth and decay of types and individuals are of 

 great interest, as they afford organic conditions under which the 

 principles of transformation must act. 



After considering certain general propositions that apply 

 equally to all of the eight principles above enumerated, I shall 

 consider more particularly what the effect of some of these prin- 

 ciples is when cooperating with Independent G-eneration, The 

 only principles I shall treat in this special way are the four 

 principles of Unbalanced Propagation. 



The Tbansfoemation of peeelt Inter generating Organisms 

 NEVER Divergent. 



I mention these eight principles of transformation, not with 

 the purpose of entering upon a full discussion of the same, but 

 simply to point out the relation in which they all stand to diver- 

 gent, or polytypic, evolution. It is evident that whether acting 

 separately or together, they can never be the cause of divergent 

 evolution in organisms that are freely inter generating ; for in 

 such a group of organisms whatever modifies one part of the 

 group in characters that are inheritable will ere many generations 

 modify the whole. If the group is exposed to a variety of inhar- 

 monious conditions, which with Independent Generation would 

 produce divergent character, with free Intergeneration the only 

 result will be variation. Without Segregation there can be no 

 permanent divergence ; and with Segregation there must be di- 

 vergence ; and with cumulative Segregation there must be cumu- 

 lative divergence. This principle, which I call Divergence through 

 Segregation, was the subject of my previous paper. 



Independent Teanseormatign never Parallel, but 

 ALWAYS Divergent. 



If any species is divided into two or more sections that do not 

 intergenerate and that are severally subject to highly complex 

 transforming influences, it can only be by a series of coincidences 

 which the reason refuses to receive as in the slightest degree 

 probable that any two sections will be modified in exactly the 

 same way. This high degree of probability, amounting to a 

 certainty, that when causes of transformation cooperate with 

 causes producing Separation or Segregation, the result in sue- 



