MOULT AND REGENERATION OF PELAGE IN MICE 89 



tials in growth which are due, in turn, to inequahties in the pe- 

 ripheral blood supply. We shall consider this theory more at 

 length in the discussion of his studies of the regeneration of hair. 



In the species of Peromyscus studied I find some deviations 

 from the process of moult as described by Osgood ('09) in his 

 monograph of the genus. With reference to the postjuvenal 

 moult he writes: "This [i.e., juvenal] stage is succeeded by the 

 adolescent pelage, which first appears on the middle of the sides" 

 (p. 20) . I do not find this to be the case in any of the three species 

 examined. Another difference is in regard to the regions last 

 invested. Instead of the "rump and nape usually being the last 

 parts to be covered," the juvenal pelage normally persists on the 

 head between and just anterior to the ears for days, often for 

 weeks after the complete investment of the rump region. In 

 these regards, the species in question do not appear to be typical 

 of the genus. 



The precocious appearance of feathers or hair characteristic 

 of a later plumage or pelage has been mentioned by a number of 

 observers. With reference to the varying hares, Allen ('94b) says : 



In the case of wounds from fighting or other cause, resulting in the 

 violent removal of large bunches of fur, it is interesting to note that in 

 the autumn the new hair comes out white, often weeks in advance of 

 the general change, and that in spring, under similar circumstances, 

 the hair comes out brown, like the summer coat, much in advance of 

 the general change from winter to summer pelage (p. 121). 



A similar condition has been described by Schultz ('15) in the 

 Himalayan rabbit. In this animal, which is a pink-eyed albino 

 with black feet, muzzle, and ears, the black markings do not 

 appear in the juvenal pelage. By plucking out the hair on one 

 ear, Schultz obtained animals in which one ear was black while 

 the other remained unchanged until the next pelage was assumed. 



in the domestic fowl the secondary sexual feathers which are 

 characteristic only of the adult plumage of the male may be 

 caused to appear prematurely by plucking out the undifferenti- 

 ated body feathers which precede them. According to Pearl 

 and Boring ('14), "If the juvenile feather is removed from the 

 follicle the next feather produced by that follicle will be the 



