.lcbt^ 



Fig. 72 Frontal section through procartilages of the arches of a specimen 

 killed fourteen days after operation, showing only a few procartilage cells in the 

 third and fourth branchial arches. X 37. 



Fig. 73 Frontal secton at a lower level in same specimen as in figure 72, 

 showing only a few procartilage cells in the hyoid arch and a small number in 

 first branchial arch on operated side. X 37. 



Fig. 74 Frontal section of specimen killed seventeen days after removal of 

 crest cells from hyoid and branchial regions, showing absence of ceratohyal and 

 first and second ceratobranchial cartilages on the operated side. X 37. 



Fig. 75 Frontal section of a specimen killed eleven days after operation, in 

 which an attempt was made to remove all the crest cells, .showing only rudiments 

 of cartilages in the hyoid, first and second branchial arches. The quadrate is 

 smaller than normal. X 37. 



Figs. 76 and 77 Frontal sections at two levels in the same specimen, showing 

 the small size of the right quadrate cartilage. X 37. 



478 



