MOULT AND REGENERATION OF PELAGE IN MICE 81 



Saccardo's umber to sepia, with the dorsal median stripe more or 

 less strongly marked with black. This difference in the general 

 color of the two pelages appears to be due mainly to the increased 

 amount of yellow pigment in the subterminal bands of the post- 

 ju venal hairs. 



The postjuvenal moult of two other races of California deer- 

 mice (P.m. sonorienses and rubidus) as well as in a 'yellow' 

 mutant of gambeli, which appeared about two years ago in the 

 murarium stock is essentially the same as above described. 



In two other species of Peromyscus (californicus insignis, 

 and eremicus fraterculus) which occur in the vicinity of La Jolla, 

 the process is quite similar, but upon a closer examination there 

 appear to be certain characteristic differences in the points of 

 origin and directions of growth. 



3. LATER MOULTS 



In general, in the assumption of the adult pelage and in the 

 seasonal moults, the process is the same as above described. 

 However, these later moults appear to be somewhat more irregu- 

 lar, and frequent partial moults further complicate the situation. 

 These moults will be treated more at length in a later paper. 



4. REGENERATION OF PELAGE IN JUVENAL MICE 



After having observed the rather marked regularity in points of 

 origin, sequence, and directions of growth, in the assumption of 

 the postjuvenal pelage, it seemed worth while to determine to 

 what extent, if at all, the process might be modified by the arti- 

 ficial induction of regenerative processes. 



In the series of experiments here described, a total of about 

 forty gambeli were used, varying in age from two and one-half to 

 seven weeks. The mice were etherized and the pelage was re- 

 moved by plucking out with the fingers. The hair is quite loose, 

 especially just previous to a moult, and may be very readily 

 removed in this manner without injury to the skin. 



Except in those cases where the moult was too far advanced, 

 the following regions were operated on in every individual: 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 27, NO. 1 



