CRANIAL GANGLIA OF AMBLYSTOMA 



481 



lower jaw on the operated side showed an abnormal development. 

 A dissection of this individual was made after the cartilages had 

 been stained with methylin blue and shows (fig. 78) only three 

 small branchial cartilages on the right side while the first and 

 second basibranchial cartilages are present, but abnormally placed 

 to the right of the midline. The quadrate and mandibular carti- 

 lages are somewhat smaller (figs. 79 and 80). There is not much 

 difference in the size of the anterior portions of the trabeculae. 



Fig. 78 Showing a camera-Iucida drawing of a dissection of cartilages stained 

 in methylene blue. Killed twenty-one days after operation. An attempt was 

 made to remove all the neural crest in this specimen. Only three small branchial 

 cartilages appear on the operated side. The first basibranchium is less developed 

 on the right side, while the second basibranchium is a slender rod and displaced. 

 The right mandibular cartilage also appears smaller than the normal. X 23. 



Figs. 79 and 80 Camera drawings of lateral views of a dissection of specimen 

 figured in 78, showing, respectively, operated and normal sides. The quadrate 

 and mandibular cartilages are smaller on the operated side. X 23. 



Fig. 81 Frontal section, showing in another specimen at the level of the optic 

 nerves relative sizes of the quadrates when the crest cells have been removed at 

 stage 24. X 37. 



