CONTENTS. 



Page. 



Continuous versus discontinuous variations as factors in evolution .... i 



Variations of rats in coat-color and coat-pattern 4 



Mendelian inheritance of coat-colors and coat-patterns in rats 7 



Albinism recessive in relation to all types of pigmentation 7 



Latent pigment characters and coat-patterns 8 



Modification of hooded pattern by crossing with Irish 1 1 



Modification of hooded pattern by selection 14 



Selection for reduced stripe 14 



Selection for stripe of increased size 17 



Individual spots of guinea-pigs not unit characters 18 



Color-patterns selected 18 



Dutch-marked series (Series D) . 20 



Head-spot series (Series //) 23 



Statistical analysis of the data for Series D and // 25 



Nose-spot series (Series N} 26 



Conclusions 32 



Tables 34 



Bibliography .... . . 50 



in 



