F. Pitt 107 



and by analogy with the behaviour of similar pigmentary characters in 

 other species it is probably the latter. If we are right in supposing that the 

 red coloration is due to the absence of the factor for black, it becomes 

 at once apparent that it would be a most difficult task to decide how and 

 when the factor first fell out. The tendency to the red coloration might 

 lie latent for many generations until a suitable mating brought together 

 gametes from both of which the factor was missing. It must be remem- 

 bered that the dark offspring of a red x dark mating would necessarily 

 be heterozygotes, of the constitution DBdB (I am herein using the 

 letter " D " to indicate the dark black-brown colour, " B " the light red- 

 brown, "db" the absence of all pigment or albinism), and if such heterozy- 

 gotes are fairly widely distributed it would account for the sporadic way 

 in which the red-brown individuals have turned up during the last 

 seventeen or eighteen years since the first specimens were obtained. It 

 is evident that in this variety of the polecat we have not really anything 

 new, for the factors for it have undoubtedly been latent in the animal's 

 constitution since it assumed its present type of coat and colouring. 



(b) Variation in the Ferret. We may confidently assume that in the 

 pigmented and so-called " polecat " ferret (known among keepers and 

 rabbit-catchers as the " fitchet ") we have a near approach to the 

 ancestral type, from which the well-known white form is almost certainly 

 an albinistic mutation. Erythristic ferrets analogous to the reddish- 

 brown polecats are also met with, but, as the " fitchet " ferret is paler 

 than the dark brown-black wild polecat, so is the fawn ferret paler than 

 the " red " polecat, being much more " washed-out " looking. It is 

 evident that we here meet with similar if not identical pigmentary 

 characters to those found in the polecat, therefore the same letters may 

 be used to denote the factors, D for dark black-brown or full pigmenta- 

 tion, B for light red-brown, and so on. 



A detailed account of the behaviour of the black-brown pigmentary 

 character will be given later on under the heading Ferret-Polecat 

 Hybrids, and I will now confine myself to the erythristic variety. The 

 exact tint of the fur is best described by the word " sandy." The colour 

 is confined to the long outer hairs, the woolly undercoat being white. 

 As in the red-brown polecat the absence of black pigment is correlated 

 with size and vigour. Most of the sandy ferrets I have seen have been 

 exceptionally fine animals. They are also noticeably quicker tempered 

 than dark or white ones. It is my experience that they require a good 

 deal more handling to keep them quiet and docile, and even then cannot 

 be trusted. One sandy ferret I had was called " Ginger " on account of 



