576 



Bulletin 318 



pullets of similar age and parentage. In these two pens of strong pullets 

 there were consequently, at the start, no weak individuals, but only 

 pullets that were strong and healthy. 



The average weight of the low- vitality White Leghorn pullets in experi- 

 ment II at this period was 3.56 pounds, while that of the high- vitality 

 comparison flock was 3.74 pounds. The Barred Plymouth Rock pullets 

 in the low- vitality flock (experiment III) averaged 3.9 pounds and their 

 stronger sisters 5.2 pounds. 



In order to interpret intelligently the tabulations that follow, it is 

 necessary to bear in mind the exact conditions surrounding each flock 

 chosen for these comparisons. Only one selection was made. If a fowl 

 in the strong pens became weak or one in the weak pens gained in strength, 

 it was neither removed nor transferred. 



Fig. 



160. — The htiildings in which flocks y8 and 79 were 

 housed 



THE KIND AND SIZE OF HOUSES AND YARDS 



The flocks to be directly compared were placed in houses identical 

 in size, shape, equipment, and exposure, with yards of equal size and under 



similar cultivation . 

 Each house was 

 equipped with trap 

 nests and the usual 

 feed cans, hoppers, 

 and water pans. 



Flocks 78 and 79 

 were put in colony 

 houses of the gable- 

 roof type, shingled and 

 tightly constructed 

 (Fig. 160). These houses had board floors laid near the ground. There 

 were no glass windows. One large cloth window, with its lower edge 

 about 3 feet above the ground, served to admit light and provide venti- 

 lation. Each fowl was allowed 4.8 square feet floor space, 42 cubic feet air 

 space, 0.6 square feet cloth- window opening, and 12.4 square feet yard 

 area. In these small yards the soil soon became bare. 



Flocks 76 and 75 were given colony houses of the shed-roof type, with 

 paper-covered roofs (Fig. 161). The board floor in these pens was raised 

 about I foot above the ground. These houses were also without glass 

 windows, but a large adjustable cloth curtain provided abundant ventila- 

 tion and allowed sufficient sunlight to enter. The opening covered by 

 this curtain was about 3 feet above the floor. Each fowl was given 4 

 square feet floor space, 22.4 cubic feet air space, 1.36 square feet cloth- 

 window surface, and 43.9 square feet yard area. 



