| OCR Text |
Show 1903.] IN FANCY MICE AND RATS. 73 withstand the treatment more than 24 hours, though ultimately it also (and the keratin) disappears. The brown may be present in both medulla and cortex; the black is chiefly deposited in the medulla, but may be cortical also, while it is doubtful whether the yellow is ever present except in the medulla. All these pigments may coexist in the same hair; but hairs are found with only black and brown, others containing only black and yellow. Other types possibly occur. The lighter colour is mostly peripheral (in hairs which contain other colours), but brown often is present in the cortex at levels where the medulla contains black. In M. sylvaticus the condition is similar, but the amount of black is less. The different colour-types of fancy mice are due to the presence or absence of one or more of these pigments in various amounts. Both the yellow and the brown may exist separately, without any other pigment being discoverable, but, so far, no mouse has been seen having black only, some brown being always associated with black. Each chief type of coloration, black, brown, and yellow, exists in at least two forms--the one more intense, the other more dilute. The dilution, which affects both medulla and cortex, seems to be due to greater scarcity of the pigment-granules, not to diminution in their size. The following list includes all the types examined, though some probably remain to be seen. Waltzing mice, so far, have not been examined. The fanciers' names are generally retained, as on the whole distinctive and practical. Owing, however, to the ambiguity in the use of the term "fawn" to denote both "yellow" and colorations containing other pigments, the term " yellow" is used for the type containing yellow pigment only. 1. Ordinary Cinnamon (or Agouti). The colour of M. muscvhis, having same three pigments. Exists in at least two strains, one rather darker than the other. This is doubtless the " grey" of most writers. Pied forms and strains common. 2. Golden Agoitti. Like (1) but yellower. Contains brown and yellow, without black. 3. Sable. This rather striking type is like (1) on the back, but with yellow hairs interspersed at sides. Flanks almost wholly yellow. Pied with white this colour gives the so-called " tricolor." 4. Blue-and-tan. Not examined microscopically. [Probably sable in which black is diluted.] 5. Chocolate = Plum. Contains brown alone. May be pied. 6. Silver-fawn. A diluted form of (5). Many hairs have colourless tips. 7. Yellow. Contains yellow only. Often called " fawn," though this term is also applied sometimes to colour containing brown or black. W h e n dark pigment is present in association with predominant yellow the colour is spoken of as " dingy " or " sooty fawn." |
