Chap. I.J RUDIMENTS. 25 



above the eyes, where the true eyebrows, if present, would 

 have stood. 



The fine wool-like hair, or so-called lanugo, with which 

 the human foetus during the sixth month is thickly cov- 

 ered, offers a more curious case. It is first developed 

 during the fifth month, on the eyebrows and face, and es- 

 pecially round the mouth, where it is much longer than 

 that on the head. A mustache of this kind was observed 

 by Eschricht 30 on a female foetus ; but this is not so sur- 

 prising a circumstance as it may at first appear, for the 

 two sexes generally resemble each other in all external 

 characters during an early period of growth. The direc- 

 tion and arrangement of the hairs on all parts of the foetal 

 body are the same as in the adult, but are subject to much 

 variability. The whole surface, including even the fore- 

 head and ears, is thus thickly clothed ; but it is a signifi- 

 cant fact that the palms of the ha'nds and the soles of the 

 feet are quite naked, like the inferior surfaces of all four 

 extremities in most of the lower animals. As this can 

 hardly be an accidental coincidence, we must consider the 

 woolly covering of the foetus to be the rudimental repre- 

 sentative of the first permanent coat of hair in those 

 mammals which are born hairy. This representation is 

 much more complete, in accordance with the usual law of 

 embryological development, than that afforded by the 

 straggling hairs on the body of the adult. 



It appears as if the posterior molar or wisdom-teeth 

 were tending to become rudimentary in the more civilized 

 races of man. These teeth are rather smaller than the 

 other molars, as is likewise the case with the correspond- 

 ing teeth in the chimpanzee and orang ; and they have 

 only two separate fangs. They do not cut through the 

 gums till about the seventeenth year, and I am assured 

 by dentists that they are much more liable to decay, and 



80 Eschricht, ibid. a. 40, 47. 



