Casting Off the Useless Organs 



the ones still functioning on the forehead and in some 

 instances, the entire scalp. 



It will be remembered that the fish purify their blood 

 by extracting the oxygen from the water as it passes through 

 their gills which are separated by slits or openings usually 

 five or seven in number and which open into a chamber on 

 each side of the neck or head. After the head takes form 

 in every mammalian embryo, the next most prominent fea- 

 ture of the entire embryonic structure is that of the gill slits 

 or openings on each side of the neck. So persistent is Nature 

 in repeating the life forms of the past that there are many 

 children born with these gill slits plainly visible being cov- 

 ered only with skin and in some cases, the openings are com- 

 plete. In a short time after birth, these openings close but 

 in many instances, some semblance of their markings are 

 carried through adult life. Nature has made use of many 

 outgrown organs by adapting them to some other useful 

 purpose and one of the strangest facts which the science of 

 Anatomy has brought to a common understanding is the 

 fact that Nature has constructed the external and middle ear 

 of the human species from the first cartilagenous gill opening 

 and its surrounding parts. 



The ancestral fish In the chain of life had developed 

 lungs capable of extracting oxygen from the air before pass- 

 ing on to the Amphibian class. Up to this time, the sense of 

 hearing did not exist. This sense was developed millions of 

 years later than the sense of sight. But an organ capable 

 of giving the brain a warning signal against the approach 

 of danger and of receiving beneficial messages conveying 

 human and animal thought was necessary for an advance- 



[263] 



