196 



K. S. LASHLEY 



TABLE 19 



months. At the end of this time a record was kept of all the 

 progeny of the last selected generation in each of the 50 lines. 

 The continued freezing of the food pond made it necessary to 

 bring the experiment to a close when an average of 12 buds 

 had been obtained from each of the members of the last selected 

 generation. The selection covered an average of 6.08 gener- 

 ations in the group selected for seven or more tentacles, and of 

 7.92 generations in the group selected for six or less. The average 

 number of tentacles of all selected generations of the plus selected 

 group was 7.008, that of all selected generations of the minus 

 selected group was 5.560, giving an average of 1.448 tentacles 

 as the amount of difference per generation between the selected 

 ancestors of the two groups. 



The first effect of the selection was a marked reduction in the 

 vitality of the group selected for a small number of tentacles. 

 The rate of budding of the group was reduced and some of the 

 polyps showed symptoms of slight depression. Four of the buds 

 of the last selected generation of this group, after maturing and 

 producing from four to eight buds, went into a depression which 

 lasted for a week or more and were revived only with difficulty. 

 The reduction in the vigor of the minus selected group intro- 

 duces a complication into the study of the effects of selection, 

 for the transmission of reduced vitality, or of characters depen- 

 dent upon reduced vitality, is not a proof of heredity, unless, 

 indeed, the changed condition prove quite permanent. 



The total number of progeny obtained from the last selected 

 generation was 583, of which 309 were from the parents selected 

 for a large number, and 274 from those selected for a small 

 number of tentacles. The distribution of variations in the two 



