424 



RUTH J. STOCKING 



After December 23 every one of the lines belonging to race 

 A was carried on in two parts or sub-lines; in one sub-line the 

 most normal individuals were selected; in the other sub-line the 

 most abnormal individuals were selected. This procedure kept 

 going a number of normal-selected lines up to as many as 40; 

 and an equal number of abnormal-selected lines. In almost all 

 of the normal-selected lines the continuous selection of normals 

 was not possible; some generations were entirely abnormal, no 

 normals at all being produced. But 62 days after this normal 

 selection had begun, one normal was isolated which gave rise to 

 six lines in which the continuous selection of normals was possi- 

 ble for some time before they died out. Their history is given 

 in chart 5, and the data afforded by them in table 10. The 

 largest of these six lines was kept for 26 days after the con- 

 tinuous selection of normals was begun and gave rise to 22 gen- 

 erations of normals. There were 42 individuals in the observed 

 cultures of this one line; one of these was abnormal; all the rest 

 were normal. 



TABLE 10 



Data from the six lines of Race A in which the selection of normals was 



continuous 



As all the animals of these six lines were descendants of one 

 normal individual present on February 27 (chart 5), they can 

 all be counted together as one group, which will give 134 normal 



