MOULT AND REGENERATION OF PELAGE IN MICE 85 



cally, as has been already indicated,^ replacement after depilation 

 occurs simultaneously over the whole region. 



A further reminder of the normal process was noted in the 

 mode of regeneration on the head. Instead of the fairh^ uniform 

 replacement usually observed after depilation, there were two 

 independent centers of growth. Pigment (followed in a few days 

 by the incoming hair) first appeared on the snout just below the 

 level of the eyes, spreading anteriorly to the tip and posteriorly 

 to a definite transverse line connecting the anterior insertions 

 of the ears, the skin posterior to the line remaining unpigmented 

 for several days. In another member of the brood pigment 

 developed at the same time on the snout and back of the ears, 

 leaving a small patch of pigmentless skin between them. 



The incoming post ju venal pelage does not ordinarily trans- 

 gress the limits of the depilated region and, as a rule, the mode 

 of change on the rest of the body surface remains unmodified. 

 Occasionally, however, there is apparent^ some 'action at a 

 distance.' One such case has already been cited.*' In another 

 instance, where the juvenal pelage had been removed from the 

 hips, the incoming post juvenal, passing be3^ond the denuded 

 region, extended anteriorly to the middle of the dorsum, meeting 

 at this point the normal moult which was proceeding in the 

 opposite direction. In other words, the normal direction of 

 growth had been reversed on a part of the dorsum which had not 

 been operated upon. 



In all cases where the juvenal pelage was removed it was 

 replaced by the post juvenal. However, I have noted what at 

 first appeared to be an abortive attempt to regenerate juvenal 

 hairs. 



During the week following the removal of the juvenal pelage 

 (in those cases only in which the skin was dark at the time) 

 a growth of fine short blackish hairs appeared on the denuded 

 areas. This was succeeded in a few days by the incoming post- 

 ju venal hair. 



' See page 83 above. 

 ' See page 83 above. 



