Vlll FOREWORD 



" Now from the best accounts he had been able to get of this matter, he 

 was satisfied it could not be where Des Cartes had fixed it upon the top 

 of the pineal gland of the brain, which, as he philosophized, formed a 

 cushion for her about the size of a marrow pea ; this to speak the truth, 

 as so many nerves did terminate all in that one place, it was no bad 

 conjecture." 



Readers will remember how Uncle Toby knocked the bottom out of 

 Descartes' theory by relating the case " of a Walloon officer at the battle 

 of Landen, who had one part of his brain shot away by a musket ball — 

 and another part of it taken out after by a French surgeon, and after all, 

 recovered and did his duty very well without it." 



I need not anticipate the conclusions reached by our authors regarding 

 the nature and function of the pineal body of the human brain ; they will 

 be found in the concluding chapter of this book. In spite of all their 

 labours, much remains enigmatic concerning the pineal body ; but they 

 have laid a basis from which those who would go further must set out. 



I must not be like a too loquacious chairman and abuse the privilege 

 the authors have given me, in writing the foreword, by intruding my own 

 opinions. Yet at the risk of sinning in this respect, there are one or two 

 observations I have picked up in my recent reading, which seem to throw 

 light on some of the problems discussed by them. There is first an 

 observation made by Wislocki and King {Amer. Journ. Anat., 1936, 58, 

 421), who on injecting a solution of trypan blue in the live animal, found 

 that it stained certain nuclear structures in the hypothalamus and also the 

 cells of the pineal body — an outgrowth from the epithalamus. There are 

 structural resemblances in the parts so stained. Such an observation fits 

 easily into the final conclusions drawn by our authors. Hypothalamus 

 and epithalamus, so widely separated by the thalamus in the human brain, 

 were anciently close neighbours, both being associated with olfactory 

 tracts and connections. Both are constituent parts of that cavity of the 

 brain from which the lateral eyes as well as the median or parietal eye are 

 developed. 



Our authors find that the evidence which attributes a sex function 

 to the pineal body is confused and contradictory, and rightly in my opinion 

 bring in, on this head, a verdict of " unproven." Before we finally reject 

 the evidence, however, it seems well to remember that through our retinae, 

 there are transmitted to the brain not only stimuli which give rise to vision 

 but also " light reflexes." It seems probable that the median as well as 

 the lateral eyes had this double function. Through centres in the 

 hypothalamus and pituitary, light reflexes can bear in upon the gonads 

 and regulate their times of ripening. Prof. Le Gros Clark and his 



