NATURE 



2T I 



THURSDAY, APRIL 22, 1009. 



MAIL'S HAIRY COVERmG. 

 Beitriige zttr Natiirgeschichte des Mensclten. Liefer- 

 ung i., Das Wollhaarkleid des Menschen (7 coloured 

 and 3 uncoloured plates); Lieferung ii., Das Dauer- 

 haarldeid des Menschen (6 coloured and 7 un- 

 coloured plates) ; Lieferung iii., Geschlechts- und 

 Rassenunterschiede der Behaarung, Haaranimalien 

 und Haarparasiten (g coloured and 4 uncoloured 

 plates); arrd Lieferung iv., Entwicklung, Bau und 

 Entstehung- der Haare, Literatur iiber Behaarung 

 (7 coloured plates). By Dr. Hans Friedenthal. Pp. 

 31 + 39-1-49 + 57. (Jena: Gustav Fischer, 1908.) 

 Prices of volumes : 10, 20, 20 and 15 marks 

 respectively. 



THE distribution of the hair, its characters, and 

 the curious phases of its growth present such 

 obvious features of contrast between man and the 

 other hair-clad vertebrates, as well as such marked 

 differences in the various races of mankind, that they 

 have formed a very frequent theme — the author of 

 the work before us quotes the titles of more than 

 1270 memoirs, and says that the list is far from 

 complete! — for the anatomist, zoologist, and anthro- 

 pologist. Moreover, the anomalies of growth and 

 distribution of hair are often forced upon the atten- 

 tion of pathologists and medical practitioners. 



The author of this bulky monograph on the human 

 hair calls his work a research on the phvsiology of 

 " Behaarung," and explains his purpose by the state- 

 ment that a knowledge of mankind which deals with 

 morphology only and does not include phvsiology in 

 its scope cannot be other than partial and unsatisfac- 

 tory. His aim in this work has been to explain the 

 interdependence of structure and function ; to show 

 that the position of man as a being set apart from 

 other mammals, so far as many features of his hair 

 equipment are concerned, is correlated with the corre- 

 spondingly distinctive nature of his (pva-K ; and to 

 indicate that anthropology is a field of research for 

 the physiologist. 



It is a well-known fact that the growth and distri- 

 bution of the hair may be strangely influenced by 

 internal secretions, especially of the genital glands. 

 The development of the distinctive arrangement of 

 the " terminal " hair at puberty is determined by 

 the activity of these glands. Premature stimulation 

 of the ovary, as, for example, by a malignant growth, 

 leads to a precocious development of pubic hair. Mal- 

 formations of the generative organs are sometimes 

 associated with an altered distribution of hair re- 

 sembling that of the other sex. After the hair dis- 

 tinctive of sexual maturity is fully developed, the 

 ovary seems to exercise a restraining influence on 

 the further growth of the body-hair (in contradistinc- 

 tion to the influence of the testicle in the male), for 

 when the influence of the ovarian secretion is with- 

 drawn .it the menopause there is often a renewed 

 activity in the growth of hair on the face and body 

 in women. 



NO. 2060, VOL. So] 



But the physiological study of hair is not limited 

 to the examination of such phenomena. According 

 to Dr. Friedenthal, the intimate relationship that 

 exists between the hair and the nervous system is 

 responsible for the result that the emotional state 

 of the individual is able to exert an influence on the 

 growth of hair by reflexly affecting the blood supply 

 of the hair roots. Moreover, in addition to this little- 

 recognised relationship between hair-growth and the 

 emotional life, there is a further intimate correlation 

 between man's mental isolation and his physical 

 isolation as a relatively hairless primate. The hairy 

 covering of the body, which is necessary for the 

 protection of most mammals, interferes with the 

 sensitiveness of the skin as a tactile organ. By such 

 an argument Dr. Friedenthal pretends that the height 

 of man's intelligence is associated with his isolation 

 among hairy mammals as a relatively hairless being, 

 because the fulness of his mental life stands in inti- 

 mate relationship with the number of impressions 

 pouring into his brain. I need not follow him in his 

 further flights into the ps5-chological significance of 

 hair, except to mention his curious conception of one of 

 the uses of the woolly hair (lanugo) of the unborn 

 child as an instrument for " reinforcing the feeling of 

 contact between mother and child " and awakening 

 the maternal instinct ! 



On the purely morphological side the author has 

 made some very interesting observations. At the 

 present time, when Schwalbe, Kohlbrugge, and 

 D wight are suggesting doubts as to man's affinity 

 to the apes, the author is justified in emphasising 

 once more, not only their general points of identity 

 of structure, and especially the striking similarity in 

 the arrangement of the hair, but also the positive 

 evidence of a " blood-relationship " which the 

 biological precipitin tests of blood afford. 



There is a striking resemblance between the dis- 

 tribution and hmits of the absolutely hairless skin 

 areas in man and the anthropoid apes. However, the 

 skin on the back of the ungual phalanges of both 

 fingers and toes and on the outer part of the back 

 of the foot in the human fcetus is quite free from the 

 hair rudiments which are found in the chimpanzee 

 in these situations. The distribution of the temporary 

 hair (lanugo) of the human foetus presents the closest 

 resemblance to that of the permanent hair of the 

 American apes, both Cebidae and Hapalidse; 

 whereas the distribution of the hair which develops in 

 the human being at the time of sexual maturity 

 recalls that of the overgrown hair-tufts of the old- 

 world apes. In a series of other features the human 

 hair is disposed like that of various apes, in contra- 

 distinction to the arrangement found in other 

 mammals, not excluding even the lemurs. 



The work treats in considerable detail of the nature 

 and significance of lanugo ; the racial and sexual 

 variability of the permanent hair, which develops in 

 early childhood, and the " terminal " hair, which de- 

 velops at puberty or during the period of maturity ; the 

 texture of the various kinds of hair and its mode 

 of insertion in the skin, its coloration, its anomalies 

 of distribution and of excess or defect, the changes 



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