440 RUTH J. STOCKING 



one abnormal which died before dividing, and one normal which 

 gave rise to two entirely normal lines which were kept for ten 

 days and eleven generations. They comprised 115 observed 

 individuals, all normal. The other abnormal present on Janu- 

 ary 19 divided to form one abnormal (which died before further 

 division) and eleven normals. Nine of these were kept. Six 

 of them gave rise to lines which remained entirely normal; three 

 produced abnormal lines. Two of these abnoimal lines remained 

 abnormal throughout their history, never responding positively 

 to the normal selection they underwent. From the other abnor- 

 mal line five entirely normal lines were split off, kept for a number 

 of generations varying from 6 to 24. Three of these normal 

 lines were kept until April 1; their eight abnormal sister lines 

 were also kept until April 1, 77 days after conjugation. 



Since all six lines had very similar histories they will not be 

 given in detail. The main facts as to the production of the 

 normal lines can be gathered from the pedigrees (pages 436 to 

 439) and the table (pages 421-422). 



Thus on the whole the work on selection shows that with 

 relation to these abnormal characteristics heritable variations 

 are in many races occurring during vegetative reproduction. 

 By selection the effect of these variations may be accumulated, 

 so that while one part of the race remains abnormal, or even 

 increases the proportion of abnormal individuals, another part 

 greatly decreases the proportion of abnormality, or becomes 

 entirely normal. The general bearing of these results will be 

 discussed after the rest of the facts have been brought out. 



Relation to hiparental inheritance 



Does conjugation tend to produce similarity in respect to 

 abnormality or normality between the progeny of the two indi- 

 viduals that conjugate? That is, if the descendants of one of 

 the two members of a given pair are abnormal, is there a tend- 

 ency for the descendants of the other member to be abnormal 

 also? If a given stock is abnormal, is the stock derived from the 

 mate of its progenitor likely to be abnormal also? Jennings 

 and Lashley ('13, '13a) have shown that there is such a tend- 



