HEREDITY AND VARIATION. 29 



cnt only in those periods of the phylogenetic line 

 in which the idioplasm, and together with this the 

 individual, do not possess the obtainable maximum 

 of adaptation to their environment for the time 

 being. Both of these variations of the idioplasm 

 take place so slowly that only after a long series of 

 generations do the new determinants become capa- 

 ble of developing and revealing themselves in the 

 transmutation of visible characters. 



Aside from the phylogenetic variations already 

 named, which take place according to the measure 

 of ontogenetic growth, the idioplasm undergoes, as 

 a result of crossing, as well as in changes of the 

 ontogeny, gamogenic variations which may be 

 designated as stationary, since in the mingling of 

 sexually different idioplasms there arise only new 

 arrangements of determinants already present, but 

 no new formation of determinants takes place. 

 Hence in this way arise also new combinations of 

 developmental characteristics. 



As a result of external injurious influences, 

 abnormal variations, or pathological variations, 

 appear in the idioplasm. These consist of disturb- 

 ances of equilibrium, which take place also without 

 new formation of determinants. Thereby the 

 determinants already present are caused to develop 

 in abnormal relations, and mostly in reversions. 



Apart from the inheritable variations of the idio- 

 plasm just enumerated, and the transformations of 



