THE EVOLUTION OF MAN 



AMPHIOXUS LANCEOLATUS, 



and its development in the egg. This development shows cross- 

 sections, first of a hollow ball, then of the stage when this ball 

 begins to double up, until an almost closed body with skin and 

 stomach membranes and one orifice is formed. The last stage 

 represents the so-called Gastrula. 



Ill 



