Labyrinthine Nystagmus. 



75 



period of metamorphosis. Of these the control showed hind legs 

 two months after the operation and the other had not developed 

 legs four months after the operation. 



Serial sections were made of eight experimental frog larvae. The 

 operation was seen to have prevented development of the thyroid 

 gland in all but one case. The hypophysis as compared with that 

 of the controls showed no changes in size or structure to be attri- 

 buted to loss of the thyroid gland. 



Among the Amblystoma larvae none developed abnormal gills. 

 The average growth rate of the experimental larvae was less than 

 that of the controls, but of the fourteen which were alive, after three 

 months, the largest had had the thyroid removed. In none of the 

 thirteen operated animals that were sectioned was there any re- 

 generation of the thyroid. There were no changes in the hypophy- 

 sis nor in the pigmentation of the skin following the thyroidectomy 

 during the three months in which the operated larvae were under 

 observation. 



48 (1226) 



The effect of decerebration upon the quick component of laby- 

 rinthine nystagmus. 



By F. H. Pike. 



[From the Department of Physiology of Columbia University.] 



The effects of decerebration have been variously held to show 

 (1) that the central cells of certain reflex mechanisms are located 

 in certain definite regions or levels of the central nervous system, 

 and (2) that certain other reflex mechanisms do not have their 

 central representation in the same regions or in other regions, 

 There has been little consistency in drawing conclusions from the 

 results of decerebration, and frequently other considerations have 

 entered into the matter to such an extent as to outweight the ex- 

 perimental results of decerebration. In addition, the experimental 

 results as reported by various investigators are not in agreement, 

 and one notices a lack of post-mortem reports as to the extent to 

 which destructive hemorrhages have burrowed downward from 

 the level of transection of the brain stem, or on other conditions 



