MOULT AND REGENERATION OF PELAGE IN MICE 93 



Betrachtet man die Riissenkaninchen als Ganzes, so erhiilt man den 

 Eindruck, dass an ihnen die mehr innen gelegenen Teile farblos bleiben, 

 daher nicht nur die andern inneren Gewebe, sondern sogar die roten 

 Aiigen, welche nach innen versenkt sind. Die dem Herzen ferneren, 

 den Schadigungen der Aussenwelt und der schlechteren Durchblutung 

 mehr ausgesetzten Teile, Nase, Schwanz, Ohren, Fiisse, sind der Farb- 

 bung verf alien, uberhaupt neigt daher insbesondere die Haut ziir 

 Farbstoffbildnng. Die inneren Organe scheinen gerade wegen ihrer 

 besseren Durchblutung, geringeren Schadigung wegen Farblosigkeit 

 zu besitzen (pp. 551 and 552). 



That is to say, pigment formation is most pronounced where 

 the processes of growth are most active, and at the same time, 

 in regions having a relatively poor blood supply. From which it 

 appears to follow that an adequate supply of blood tends to 

 inhibit growth. 



It appears that, at best, Schultz' theory of the relation of blood 

 supply to pigmentation is applicable only in a limited number of 

 cases. The list of exceptions is overwhelmingly large. 



To cite a specific case, the hair on the feet of Peromyscus is 

 pigmentless. This is characteristic of the genus, whence the 

 name, 'white-footed mice.' 



Furthermore, in many species of small mammals, individuals 

 having white-tipped tails are of frequent occurrence. In the 

 case of Zapus insignis, as cited by Miller ('93), this white-tipped 

 condition has become characteristic of the species. In certain 

 species of Peromyscus, Sumner ('18) describes the occasional 

 appearance of the same character, and of pigmentless snouts as 

 well. In the alternative inheritance of many color patterns, 

 we are confronted by another categbry of facts which are not 

 readily interpreted in the light of Schultz' hypothesis. 



In conclusion, we may refer to the interesting and suggestive 

 researches of G. M. Allen. This investigator has found that in 

 general in mammals and birds, pigmentation centers in eleven 

 separate areas, five paired, and one unpaired. Pigmentless 

 markings are said to arise when contiguous areas fail to meet. 

 Each area may vary independently. 



Further investigations along these lines may go far toward 

 clearing up some of the puzzling problems which one encounters 

 in a study of animal coloration. 



