162 THE GROWTH OF GROUPS 



raised from it a vast number of individuals through many 

 generations. Contrary to expectation these were not all 

 of one kind. Although there were thousands of instances 

 to confirm the rule that like gives birth to like, yet there 

 were occasional exceptions to that rule. A number of 

 other kinds were given off from time to time from the 

 original parental line, i.e. produced from the self -fertilized 

 seed of 0. lamarckiana. These other kinds were so 

 definite that they could be recognized without doubt. 

 It is important to note that the several kinds had not an 

 equal chance of survival in apparently similar circum- 

 stances. Some kinds were able to give rise to long lines of 

 healthy progeny, others, although thrown off from the 

 parental stock, on many occasions were unable to establish 

 themselves. After every occasion of origin they quickly 

 disappeared. 



In the words of De Vries, " The causes of such disap- 

 pearances are mainly three : (i) sterility, or at any rate 

 insufficient fertility; (2) constitutional delicacy; (3) inability 

 to breed true." We are beginning to recognize that the 

 so-called unfit mutant is a common product of the tree 

 of life, and perhaps we shall recognize eventually that 

 those mental disorders that are not the result of an 

 external agent, should be regarded as unfit mutants. 



This assumption is based on the fact that such cases 

 of mental disorder may be classified in groups and sub- 

 groups, that the same type of disorder may arise again 

 and again on various occasions in separate parts of the 

 world. Though transmissible to some extent, like the 

 unfit mutants of (Enothera, they cannot persist for similar 

 reasons. 



It is unnecessary to explain the mutants of (Enothera 



