170 



STUDY OF PIG EMBRYOS. 



Figure 109 gives an outline of the head and combines an indication of the 

 extenal modeling of the gill arches with a representation of the shape of the 

 pharynx. 



Pig Embryo of 15 mm. — As compared with figure 99, the present 

 embryo (Fig. no) has not only grown in all its dimensions, but has also 



1 ic no. — Pig Embryo of 15 mm. X S diams. 



changed in form. Unlike the embryo proper, the umbilical cord has 

 grown very little. We notice at once that the outline of the back is 

 less curved than before, the ventral side of the body has acquired a con- 

 vex outline, and at the head it has become considerably larger, both abso- 



