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THE AMERICAN NATURALIST [Vol. LIII 



birds of the original flock were divided into groups ac- 

 cording to the percentage of net increase (or decrease) 

 in the mean weight of eggs laid during the period of the 

 vernal maximum (April). The percentage-groups were 

 based on the scale indicated in the accompanying table. 



From the data presented in Table I it is apparent that, 

 on the average, the birds that showed the higher per- 

 centages of increase in the weight of the April eggs were 

 also characterized by the higher productions. Those 

 characterized by a weight-increase of 10 per cent, or 

 more showed a mean production of 147 eggs, while those 

 characterized by a weight-increase of more than 3 per 

 cent, only, showed a mean production of only 122 eggs. 

 The mean production of the group characterized by a 

 decrease in egg- weight was the lowest of all— 111 eggs, 

 this being below the mean production of the entire flock. 



If the birds are divided into two groups only, one 

 having an increase of 6 per cent, or more, the other show- 

 ing an increase of less than 6 per cent, or an actual 

 decrease in egg-weight, it is found that the high-per- 

 centage group gives a mean production of 137 eggs, while 

 the low-percentage group gives a production of only 112. 

 In this instance the portion of the flock falling in the 

 high-percentage class was approximately 24 per cent.; 

 and this small group gave an average production that 

 was 23 per cent, in excess of the production of the low- 

 percentage group. The fact is thus brought out that, 

 although a certain small proportion of high-producing 

 individuals that are also characterized as manifesting 

 only a slight percentage of increase in egg-weight at the 

 period of the vernal weight maximum, will usually be 

 found, the higher producers are, on the average, char- 

 acterized by the larger percentages of increase (6 per 

 cent, or above) ; and the selection of hens on this basis 

 results in the separation of those individuals possessing 

 the highest producing value. 



