MOULT AND REGENERATION OF PELAGE IN MICE 83 



Juvenal pelage, about half grown out, almost uniform in length, 

 though slightly longer posteriorly. Those of the ventral surface 

 were also wholly covered with pelage of about uniform length. 

 In the meantime the normal postjuvenal moult had appeared on 

 the throat near the point of the jaw, extending under the ear and 

 down on the anterior face of the forelimb entirely outside the 

 depilated region and in typical fashion. At the same time post- 

 juvenal pelage, barely through the skin, was found extending as 

 a narrow band on the lateral line from the base of the tail to the 

 forelimb on one side of the body, and from the hind limb to the 

 forelimb on the other. Both strips were continuous with the 

 new pelage coming in on the posterior ventral area. Never 

 having observed this condition in a normal moult, I am inclined 

 to regard the premature appearance of postjuvenal pelage in this 

 region as an abnormality resulting from the operation. At this 

 time the depilated area on the hips was still bare. 



In the other two members of the litter the normal moult had 

 not appeared by the seventeenth day. The depilated regions 

 of the head were covered with a uniform growth of postjuvenal 

 pelage, but the hip regions showed no indications of regeneration. 



Within a few days postjuvenal pelage appeared on the hips 

 where the juvenal pelage had been removed, and a month after 

 the operation the new pelage on all the depilated areas was fully 

 grown out. At this time both surviving members of the brood 

 were approaching the 'saddle phase' of the normal moult (fig. 12). 



A comparison of the foregoing description with that -of the 

 normal moult will show the marked extent to which the normal 

 process has been modified by artificially induced regeneration. 



If replacement on the depilated areas were to follow the normal 

 sequence, the order would be as follows: 1) throat; 2) posterior 

 ventral area; 3) dorsal lumbar region; 4) dorsal head region. 

 Moreover, as already noted, the dorsal head region is normally 

 invested some weeks after the appearance of the new pelage on 

 the throat and forelimbs. 



It will be observed that growth on the depilated regions is 

 much more nearly simultaneous than is normally the case. Fur- 

 thermore, the sequence is not the same. Regeneration on the 



