38 HAROLD SAXTON BURR 



the larvae until some time after feeding had commended. When 

 it appeared, there seemed to be no correlation between it and the 

 amount of normal food, entomostraca and plant life, available. 

 Of those in the aquaria in the laboratory there were a few that 

 could not be induced, even after starving, to touch parts of other 

 larvae. The older larvae brought in were almost all maimed in 

 some part or other. On being isolated, the missing parts were 

 soon regenerated, producing perfect specimens. It is obvious, 

 then, that cannabalism is not as rare in A. puntatum as Powers 

 believed it to be in A. triginum. 



MORPHOLOGICAL EFFECTS OF OPERATION 

 /. The skull 



Normal development. The normal development of the chondro- 

 cranium of the .imphibia has been fully described. Piatt ('97) 

 has considered carefully the origin and early history of cartilage 

 in the head of Necturns. The later development has been studied 

 Winslow in 1898, by Wilder in 1903, and Gaupp, 1905. The nor- 

 mal development of the nasal cartilages^ particularly in Ambly- 

 stoma has been fully described by Terry in 1906. 



In order to grasp fully the effect of the absence of nasal epi- 

 thelium on the formation of cartilage in the head region, a brief 

 account will be given at this point of the normal development 

 as outlined by Terry and confirmed from the controls of the 

 present series of experiments. Occasion, has been found, how- 

 ever, to change the nomenclature used by Terry, preference 

 being given to the terminology of Gaupp ('05). 



The first evidence of cartilage in the head region is the ap- 

 pearance of two centers of chondrification on the latero-ventral 

 aspects of the diencephalon. From these centers the mesen- 

 chyme becomes chondrified in an antero-posterior direction form- 

 ing two rods of cartilage, the trabecular The posterior growth 

 does not concern us here and further consideration of it will be 

 omitted. 



Chondrification proceeds anteriorly until a cartilaginous rod 

 is formed reaching to the anterior face of the olfactory sac. At 



