EXPLANATION OF PLATES. 



PLATE 1. 



Colored photographs of the fur of guinea-pigs, showing grades of dilution due to different 

 combinations of the allelomorphs of albinism. The skin of each animal from which 

 fur is shown was opened along the median ventral line and a complete section across 

 the middle of the body is shown in skins 1, 6, 9, 10, and 11. But in the other skins 2, 3, 

 4, 5, 7, and 8, only a section extending from the mid-dorsal to the mid-ventral line is 

 shown. Figures 1 to 4 show agouti fur (AAEE) ; 5 to 8, non-agouti fur (aaEE) ; and 

 9 to 11 show fur in which the extension factor is wanting (ee). The uppermost row of 

 skins are intense pigrnented, all others are dilute of intensities, diminishing toward 

 the bottom of the plate. Factors A and E are written as homozygous, though this \a 

 not known in all cases. 



FIG. 1. Black-red agouti C C AAEE 



2. Dark sepia-yellow agouti Cd Cd AAEE 



3. Dark sepia-cream agouti Cd CT AAEE 



4. Light sepia-cream agouti Cd C a AAEE 



5. Black C C aaEE 



6. Dark sepiai Cd Cd aaEE 



7. Dark sepia 2 Cd C r aaEE 



8. Light sepia 8 Cd C a aaEE 



9. Red C C aaee 



10. \ellow 4 Cd Cd aaee 



11. Cream 6 , Cd C a aaee (Cd C r similar) 



PLATE 2. 



Photographs of guinea-pig skins, showing further grades of reduction in color due to albin- 

 ism and its allelomorphs. Sections of skin extending entirely across the body are shown 

 in al! cases. The arrangement is similar to that of plate 1. 



FIG. 12. Dark sepia-white agouti (red-eyed) C r C r AAEE 



13. Light sepia-white agouti (red-eyed) C r C a AAEE 



14. Albino (known to transmit agouti) C a C a AAEE 



15. Dark sepia (red-eyed) C r C r aaEE 



16. Light sepia (red-eyed) C r C a aaEE 



17. Albino (transmits only non-agouti) C a C a aaEE 



18. White (red-eyed) C r C r aaee (C r C a similar) 



19. Albino (from yellow stock) C a C a aaee 



PLATE 3. 



Colored photographs of the skins of guinea-pigs. 



FIG. 20. A half -grown guinea-pig of race C; color, pale cream. The eyes were 

 brown-pigmented. 



21. An Fi male hybrid whose mother was an albino of race B and whose father 



was a pure cutleri. Compare figures 23 and 34. 



22. An Fi male hybrid whose mother was a brown-eyed cream animal of race C 



and whose father was a pure cutleri. Compare figures 20 and 23. 



23. A pure cutleri male. 



24. A pure cutleri female. 



PLATE 4. 



Colored photographs of the skins of F 2 hybrids produced by crossing brown-eyed cream 

 guinea-pigs with Cavia cutleri. Compare figures 20, 22, and 23. 

 FIG. 25. Golden agouti. 



26. Pale black (sepia). 



27. Brown or chocolate. 



28. Cinnamon. 



29. Yellow. 



30. Albino. 



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