62 



H. E. EWING. 



25 26 27 



FIG. 2. Plot showing the 

 results of selection in isola- 

 tion No. 4, for long narrow 

 cornicles. The figures in a 

 column to the left represent 

 the lengths ol the cornicles 

 in terms of their widths 

 which in each case is taken 

 as unity. The generations 

 are numbered at the top. 

 Curve plotted as in Fig. i. 



graphically in Fig. 2. 

 are given in Table II. 



Selections Made for Long Narrow Corn- 

 icles. Isolation No. 4. 



In this isolation selections were made 

 in an attempt to increase the length of 

 the cornicles in comparison with their 

 width at their distal ends (at the corn- 

 icle-ring). Selections for only three 

 generations were made. The first selec- 

 tion was made in the twenty-fifth gen- 

 eration. The ratio expressing the mean 

 for this fraternity was 4.86 (i. e., on the 

 average the cornicles of this fraternity 

 were 4.86 times as long as broad at their 

 distal ends). The individual with the 

 highest ratio, 435!, was selected from this 

 fraternity. It gave 13 offspring that 

 were reared to maturity. The mean for 

 these 13 offspring (the twenty-sixth 

 generation) was found to be 4.77. This 

 mean is slightly lower than the one for 

 the previous generation. From the 

 twenty-sixth generation, the individual 

 with the highest ratio, 4 2 e3, was selected 

 for obtaining the next generation. It 

 gave the twenty-seventh generation, 

 producing 6 adults with a mean ratio of 

 4.82, or four hundredths less than that 

 of the mean of the fraternity from which 

 the first selection was made. 



We find then that no effects of selec- 

 tion are evident in this isolation. The 

 results obtained for isolation 4 are shown 

 The measurements and ratios obtained 



