HOW THE GLANDS INFLUENCE THE MIND 181 



arrives more quickly at the stage when the stimulus damages his 

 nerve apparatus. The electric conductivity of his skin is greater, 

 sometimes a hundred times greater, than the average. Conversely 

 the thyroid deficient type has a low discriminative faculty. Gal- 

 ton has recorded that idiots hardly distinguish between heat and 

 cold and that their sense of pain is so obtuse that some of the 

 more idiotic seem hardly to know what it is. Cretins may moan 

 but never shed tears. 



Energy and sensitivity in an individual should direct attention 

 to the thyroid element predominating in his composition. Lack 

 of energy and insensitivity to the degree of thyroid insufficiency 

 in their make-up. 



Memory, Judgment, and Poise 



In between sensitivity and energy, the sensation and the reac- 

 tion, comes a passage of the stimulus through the gauntlet of 

 the stored past experience of the individual known as memory. 

 Many hypotheses have been advanced by philosophers, psy- 

 chologists and physiologists to explain the phenomenona of 

 memory. ^To conceive of memory materially at all one must 

 admit some sort of memory trace as the basis for the persistence 

 of memory. This memory deposit facilitates the occurrence of 

 the chemical reaction constituting the memory along the same 

 path the next time. Forgetting then consists in a disappearance 

 of these memory- traces or deposits. Forgetting is greatest in 

 the first hour after remembering, more than half of the memory 

 trace being lost in that time. x - Comparison of the curve of for- 

 getting, and the curve of diffusion of a colloid like gelatine from 

 its solution, into a surrounding medium, shows them to be ex- 

 ceedingly similar. Forgetting may be explained by some such 

 loss of the memory trace or deposit into the blood continually 

 flowing by it. 

 ^The internal secretions influence the amount and duration of 

 the memory deposits. The thyroid appears to be essential to the 

 laying down of the 'memory trace. Cretins have poor memories 

 <3tt_J&£--*eten4ien~-£i4e and so cannot learn. The memory of 

 thyroid insufficients is wretched^- In the extreme grades, the 

 memory for recent occurrences becomes completely lost. Iodine 

 and thyroid increase the electric conductivity of the brain, so 

 that the memory trace must be deposited more easily in those 

 who have an excess of thyroidy Removal of the thyroid pro- 

 duces a degeneration of nerve cells and their processes, and 



