84 PROCEEDINGS OF THE ACADEMY OF [1888. 



THE DISTRIBUTION OF THE COLOR-MARKS OF THE MAMMALIA.^ 

 BY HARRISON AELEN, M. D. 



The variations in the colors of the hair and the skin are of a char- 

 acter and importance ^vhich warrant a systematic study. I have 

 ventured to fornuilate my impressions on this subject, and -wliile de- 

 parting in some degree from the directions.of approach which zool- 

 ogists have developed, I have not I trust, stated the case without 

 due regard to the views of others on this perplexing phase of obser- 

 vation. 



My main object has been to contemplate color marks as the result 

 of nutritive processes controlled by recognized biological forces both 

 in health and disease. I Avill not hesitate to treat of a perverted 

 growth in the human subject as comparable to a normal growth in 

 any member of the mammalian series. 



Statements will be made respecting the distribution of colors of 

 hair, (the superficial color, or rather the effect of the main color of 

 the hair upon the eye being here intended) of the colors of pigment 

 marks on the skin, of localized hypertro})hies and atrophies, of vi- 

 brissie, of pilose and naked warts, as though they were co-ordinates 

 of equal value. 



I have examined the museums at Philadelphia, New York, New- 

 Haven and Washington. I have consulted the illustrations of 

 works on Natural History and have made extended observations on 

 the domesticated animals especially of dogs, horses, cattle, guinea- 

 l^igs and rabbits. 



Tlie conclusions drawn at this time have stood the test of repeated 

 re-examinations and while they are not all susceptible of being held 

 as rigid deductions from the premises, they present, I think, a group 

 of tenets which may prove of interest to working zoologists. 



The subject of distribution of the hair in the human subject has 

 received attention from D. F. Eschricht" and C. A. Voigt.^ 



Both writers have taken the new-born child as a standard and 

 have described the directions of the hair in two Avays : first as it is 



^ This paper is an elaboration of a portion of an essay which constituted 

 the presidential address at the annual meeting of the American Society of Natural- 

 ists, December, 1887. 



2 Miiller's Archiv. 1837, Vol. IV, 37. 



3 Denkschr. Wein. Akad. d. Wissenschaft. 1857, Vol. XII, III Abth. p. 1. 



