FOREWORD IX 



colleagues (Proc. Roy. Soc, 1939, 126 (B), 449) by cutting the optic 

 nerves of the ferret and thus cutting off light reflexes, altered the onset 

 of the period of heat. One can best explain the connection of the 

 habenular ganglia of the pineal with the hypothalamus (through the striae 

 medullares) by supposing that the median or parietal eye did exercise an 

 influence on the hypothalamus and pituitary. Nor is it unreasonable to 

 suppose that, in connection with sex-function, there arose in the basal 

 part of the diverticulum which gives rise to the pineal organ an area or 

 segment of nerve-cells, which, like certain groups in the hypothalamus, 

 are neuro-secretory in nature. With the disappearance of the parietal 

 eye in birds and mammals, this basal part embedded in the epithalamic 

 system, persisted in them to form the pineal body. 



I count it a privilege to have had the opportunity of reading this work 

 while it was still in proof-form. I have learned much from it and I am 

 sure others will benefit from its study as much as I have done. I would 

 especially endorse a sentence in the first chapter, which reads : 



" As one branch of medicine advances it becomes repeatedly necessary 

 to fall back on the fundamental sciences for help and guidance, and realizing 

 that the investigation of these pineal tumours proved rather barren some 

 years ago, the authors determined to investigate the whole question of the 

 nature of the pineal organ from the lowest to the highest forms in the 

 animal kingdom." 



By so doing they have shown themselves to be true disciples of John 



Hunter. 



ARTHUR KEITH. 



Buckston Browne Research Farm, 

 Downe, Kent, 



October 2&th, 1939 



