396 C. H. DANFORTH 



only 300 were incubated. The 62 unused eggs were discarded 

 from time to time in small numbers whenever the capacity of 

 the incubator was exceeded, the incubator always being filled 

 from the most recently laid eggs. This method leaves no room 

 for unconscious selection as to size, shape, etc. 



A. The alcohol treatment began on April 27 and continued 

 until June 1. Beginning May 1, there were two daily treat- 

 ments averaging a little over an hour in the morning and half 

 an hour in the afternoon. In this period of thirty-six days 

 male no. 8 was kept in the alcohol vapor a total of 63 hours 

 and 11 minutes (table 1). 



Eggs were saved from May 3 to June 2. One hundred and 

 fifty were laid, all of which were used (table 2). 



Experiment 2. (March 6, 1918, to June 19, 1918). The 

 heterozygous parent in this case was a male (no. 27) hatched 

 in March, 1917, from an egg used in experiment 1-C. He had 

 the general bearing and many of the characteristics of a Leg- 

 horn. His color was white, his comb large and walnut-rose. 

 He was polydactyl, grade 3; booted, grade 2, and had an index 

 of brachydactyly equal to 75. It will be apparent by reference 

 to experiment 1 that this bird was heterozygous for the three 

 dominant characteristics with which we are concerned, i.e., 

 brachydactyly (including booting), Polydactyly, and white 

 color. 



The homozygous parents were six single-combed black Mi- 

 norca hens purchased from a local dealer who gave assurance 

 that they were pure bred and of a stable strain. Their somatic 

 appearance as well as their racial purity showed them to be 

 homozygous for the absence of the three above-mentioned 

 traits, or, in other words, they exhibited the corresponding 

 recessive characters, normal length of toes, normal number 

 of toes, and black color. 



In this experiment, therefore, all the germ cells produced by 

 the females were necessarily of one class, that tending to give 

 black chicks with normal number and length of toes, whereas 

 the germ cells of the male were expected to fall into eight classes,, 

 viz.: 



