CONTENTS. 



General Introduction. 



Page. 



1. Systematic position of the parent races 7 



2. Materials and methods 9 



The wild race 9 



One-half wild hybrids 9 



One-quarter wild hybrids 10 



Three-quarter wild hybrids 10 



One-eighth wild hybrids, and later generations 10 



Fertile males in matings 11 



Accumulation of data 11 



Part I. Color and Coat Characters. 



3. Introductory discussion 13 



4. The agouti character in the wild race and in hybrids 14 



Homozygous agoutis in crosses 14 



Heterozygous agoutis mated to non-agoutis 17 



Heterozygous agoutis mated inter se 19 



The wild agouti and tame agouti contrasted 20 



Modification of the wild agouti 22 



Modified wild agouti in crosses 25 



"Presence and absence" hypothesis applied 28 



Non-agoutis mated inter se 30 



5. Black and brown 30 



Homozygous blacks in crosses 30 



Heterozygous blacks mated with brown 31 



Heterozygous blacks mated inter se 32 



Browns mated inter se 32 



6. Extension and restriction 33 



Homozygous condition of extension in crosses 33 



Heterozygous condition of extension crossed with restriction 34 



Heterozygotes for extension mated inter se 35 



Reds mated inter se 35 



7. Color and albinism 35 



Homozygous condition of the color factor in crosses 35 



Heterozygous colored animals in crosses with albinos 36 



Heterozygous colored animals mated inter se 37 



Albinos mated inter se 38 



8. Roughness and smoothness 38 



Homozygous rough animals in crosses 38 



Heterozygous rough animals crossed with smooth animals 39 



Smooth animals mated inter se 41 



9. Other color and coat characters 41 



Uniformity and spotting 41 



Intensity and dilution 42 



Long hair and short hair 43 



10. The fertile hybrid males in color crosses 43 



11. General conclusions as to color and coat character 45 



Part II. Growth and Morphological Characteb9. 



12. Introductory discussion 47 



13. Growth 56 



The data 56 



Comparison of growth curves 58 



The averages 58 



The coefficients of variability 62 



5 



