86 H. H. COLLINS 



When subjected to microscopical examination, it was found 

 that these hairs represented the basal portions of juvenal hairs, 

 broken off in the skin at the time of the operation. In most 

 cases, the tips plainly show evidences of fracture. It is interesting 

 to note that in many of these hairs the localization of pigment 

 has been modified to a marked extent. 



Evidences of the segmental arrangement may be partially or 

 wholly obliterated. The amount of pigment appears to be some- 

 what greater than in the normal hair at this level. This increase, 

 however, may be more apparent than real, as a result of the more 

 diffuse arrangement of the granules. 



5. REGENERATION OF ADULT PELAGES 



In addition to the foregoing studies of regeneration of hair 

 in juvenal mice, a number of rather incidental observations were 

 made on adults. 



In order to facilitate the study of the details of normal moult, 

 the old pelage was removed by clipping close to the skin. In 

 all, seventeen adult gambeli were included in this series. Ten 

 of these mice were clipped over the whole body, including head 

 and limbs, while in the remaining cases the hair was removed 

 from one side only. The mode of replacement was so irregular 

 that the primary object of the experiment was not attained. 

 However^ the results from the point of view of regeneration may 

 perhaps be of some interest. 



Although obscured by various irregularities, there were some 

 vestiges of the normal process. The first evidence of growth 

 was seen, as a rule, on the throat and forelimbs. Replacement 

 on the ventral surface preceded that on the dorsum, while, in 

 general, the moult^ proceeded from before backward. 



One of the most striking and characteristic departures from 

 the normal process was the appearance of more or less numerous 

 small isolated patches of hair over the posterior half or two- 

 thirds of the body. These 'hair islands,' which were usually 



^ Since the process includes the shedding of the clipped hair, the term 'moult' 

 may properly be used in this connection. 



