OUR FACE FROM FISH TO MAN 



is far nearer in architectural plan to the shark 

 than the latter is to whatever invertebrates we 

 may choose to name as the starting-point of the 

 whole vertebrate tree of life; but such are the 

 secure judgments of comparative anatomy. 



Much that might appear mysterious and in- 

 scrutable in the anatomy of the human face may 

 reasonably be explained as a heritage from far-off 

 shark-like ancestors, which human embryos also 

 recall. Let us therefore look a little more closely 

 into the construction and functioning of the face 

 of this human prototype. 



Always remembering that the face is merely the 

 food-detecting and food-trapping mask in front of 

 the brain, we find in the shark's apparently simple 

 face a truly marvelous assemblage of instruments 

 of precision (Fig. 6). First among these food- 

 detecting devices rank the smelling organs, rosette- 

 like membranes exposed in the olfactory capsules 

 under the nostrils, capable of detecting chemically 

 the very minute quantities of blood or other animal 

 matter dissolved in sea water. These smelling 

 capsules lead by prominent nerve tracts to the 

 large forebrain, in which the smelling centers are 



the dominant elements (Fig. 81). 



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