420 RUTH J. STOCKING 



With these two exceptions, one abnormal-selected and the other 

 normal-selected, the two groups ih both sets are very much alike. 

 They show a great deal of similarity in length of life, number of 

 generations, and proportion of abnormality, the diverse selec- 

 tion having had no effect on the character of the lines. Indeed, 

 in both sets, the lines of the normal-selected group show a larger 

 proportion of abnormals. 



Thus in line C we have a race in which long continued selec- 

 tion has no effect on the inheritance of abnormalities. And these 

 results are typical of a large number of races — all those classi- 

 fied on page 399 as class 2 (97 races all together). In all of these 

 races where such a procedure was possible the selection of nor- 

 mals was carried on as long as the race lived, in an attempt to 

 establish a normal line; but with all these races this effort failed. 

 The normals selected continued indefinitely to produce abnor- 

 mal progeny in the original proportions. With these races there- 

 fore the results of continued selection are the same as those 

 obtained by the majority of investigators in uniparental repro- 

 duction: selection does not alter the inherited constitution of 

 the line nor produce two genotypes from one. 



In another set of abnormal lines however, different results 

 were reached. In twenty-five races of our three experiments the 

 single race was split up by selection into hereditarily diverse 

 groups, one group composed of lines that continued to produce 

 abnormals, the other composed entirely of normals. The main 

 facts as to these twenty-five races are given in table 8. Many 

 of these lines were kept but a short time, so there might be 

 doubt as to the precise significance of the results from them. 

 Certain lines however were kept for a very large number of gen- 

 erations and give conclusive results. This was the case with 

 the lines A and B of Experiment 1, and with the six lines of 

 Experiment 3. Some details will therefore be given as to these 

 races. 



The history of race A may be taken as a tj^ie. The excon- 

 jugant from which this arose gave rise to normal individuals 

 only for seven days, or until December 9, when eight abnormals 

 and ten normals were found on the slide. After this the race did 



