RT Journal A1 DANFORTH CH T1 Studies on hair: With special reference to hypertrichosis JF Archives of Dermatology and Syphilology JO Archives of Dermatology and Syphilology YR 1925 FD April 1 VO 11 IS 4 SP 494 OP 508 DO 10.1001/archderm.1925.02370040073005 UL http://dx.doi.org/10.1001/archderm.1925.02370040073005 AB The production of hair is one of the fundamental characteristics which differentiate the mammals from other classes of vertebrates. Hair is as peculiar to the mammals as feathers are to the bird. It is present and, with few exceptions, well developed in every member of the class, while it is entirely lacking in all other vertebrates. It was a recognition of the value of hair from the systemist's standpoint that lead Oken to propose the term Trichozoa—hair animals—for his highest class of vertebrates. Although Oken's term never came into general use, the fact remains that it is as descriptive of the class as is the word Mammalia,1 which supplanted it.It is natural that a character so distinctive and of such morphologic importance as mammalian hair should attract the attention of many investigators. During the period of intense morphologic interest, which extended through the last decades of the