X LIST OF ILLUSTRATIONS 



FIG. PAGE 



17. — A group of four young, produced by the 



animals shown in Fig. 16 ... .Facing 34 



18. — Diagram to explain the result shown in Fig. 17 35 



19. — A shortened condition of the skeleton, par- 



ticularly of the fingers Facing 36 



20. — Radiograph of a hand similar to those shown 



in Fig. 19 Facing 38 



21. — Diagram showing the descent, through five 



generations, of the condition shown in 



Figs. 19 and 20 40 



22. — A smooth, dark guinea-pig Facing 40 



23. — A rough, white guinea-pig Facing 40 



24 — A dark, rough guinea-pig Facing 40 



25. — A smooth, white guinea-pig Facing 42 



26. — A short-haired, pigmented guinea-pig Facing 42 



27. — A long-haired albino guinea-pig . . . Facing 42 



28. — Ofifspring produced by animals of the sorts 



shown in Figs. 26 and 27 . . . .Facing 42 



29. — A long-haired, pigmented guinea-pig, "Dutch- 



marked " with white Facing 42 



30. — Diagram to explain the results of a cross 



between the sorts of guinea-pigs shown in 

 Figs. 26 and 27 43 



31. — Diagram showing the kinds and relative 



frequencies of the young to be expected in 

 Fj from the crossing of animals shown in 



Figs. 26 and 27 46 



32. — Along-haired, rough albino guinea-pig Facing 46 

 33. — Five new combinations of unit-characters 

 obtained in generation Fj, by crossing the 

 animal shown in Fig. 32 with animals like 

 that shown in Fig. 22 Facing 48 



