no THE ASCENT OF MAN 



out at the neck. This last fact was so astounding 

 as to be for a long time denied. It was thought 

 that, when this happened, the orifice must have 

 been accidentally made by the probe of the sur- 

 geon. But Dr. Sutton has recently met with actual 

 cases where this has occurred. "I have seen milk," 

 he says, " issue from such fistulas in individuals 

 who have never been submitted to sounding." ^ In 

 the common case of children born with these ves- 

 tiges, the old gill-slits are represented by small 

 openings in the skin on the sides of the neck, and 

 capable of admitting a thin probe. Sometimes even 

 the place where they have been in childhood is 

 marked throughout life by small round patches of 

 white skin. 



Almost more astonishing than the fact of their 

 persistence is the use to which Nature afterwards 

 put them. When the fish came ashore, its water- 

 breathing apparatus was no longer of any use to 

 it. At first it had to keep it on, for it took a 

 long time to perfect the air-breathing apparatus 

 destined to replace it. But when this was ready 

 the problem arose. What was to be done with the 

 earlier organ ? Nature is exceedingly economical, 

 and could not throw all this mechanism away. In 

 fact, Nature almost never parts with any structure 

 * Evolution and Disease^ p. 8i. 



