282 MAINE AGRICUIvTURAL EXPERIMENT STATION. I914 



A few of the more important results which have been ob- 

 tained from this study, which has now been in progress about 

 a year and a half, may be here set forth, as follows : 



1. All feather follicles are not capable of continually pro- 

 ducing successive feathers for an indefinite time. In the case 

 of the general body plumage a feather is usually not regenerated 

 more than about three times. The precise number of successive 

 regenerations varies with different birds and different feathers. 

 Wing primaries seem to possess the maximum regenerative 

 capacity. After about the third removal in the case of body 

 feathers the follicle usually remains in a perfectly quiescent con- 

 dition, taking no steps whatever toward the regeneration of a 

 new feather. 



2. This failure to regenerate is, however, very definitely 

 related to the natural moult of the bird, and in the following 

 way. A follicle which has been absolutely inactive for a long 

 period of time (e. g., six months) preceding the natural autumn 

 moult of the bird produces a new feather in connection with 

 the moult, in the same manner as does any other follicle of 

 the body. In other words the process, of natural moulting 

 reactivates the follicle which has been brought into a quies- 

 cent state by successive feather removal. 



3. The precise pattern exhibited by a particular feather is, 

 in the usual course of events, reproduced each time a feather 

 is produced by that follicle with extreme fidelity of detail. If, 

 however, the feather is removed from the follicle as soon as it 

 is fully grown, thus forcing continued regenerative activity 

 of the follicle, the pattern tends progressively to be broken up, 

 and probably will ultimately be entirely lost as a definite 

 pattern. A progressive breaking up of an originally definite 

 pattern is clearly shown in a number of cases. The behavior 

 of the color pattern in successively regenerated feathers sug- 

 gests, as a working hypothesis, that the pattern factor or gene 

 is possibly represented in each follicle by a strictly limited 

 amount of material, and that when this is used up the pattern 

 is lost. 



4. The secondary sexual feathers of the male, such as the 

 saddle hangers, only appear as adult plumage. The same fol- 

 licles which bear these feathers produce, as juvenile plumage, 

 undifferentiated body feathers. The formation of these secon- 



