462 SCIENCE PROGRESS 



The Blood Supply and its Quality, in Relation to Growth 



and Function of the Brain 



Have nutrition and education then no influence in mental 

 development ? Let us first consider the subject of nutrition 

 from a physiological standpoint. The brain in order to grow 

 and function requires a proper supply of oxygenated blood con- 

 taining the necessary materials out of which the nervous matter 

 can be assimilated and built up. We know that if the secre- 

 tion of the thyroid gland is lacking owing to congenital absence 

 of the gland, the brain is arrested in its development, and the 

 child is a cretinous idiot. Medical science has shown that if the 

 child receives daily a small quantity of thyroid gland (obtained 

 from sheep), it stimulates the brain cells to grow and probably 

 supplies the blood not only with an excitant to growth but some 

 essential substance for the growth of the brain tissue. The 

 reason why there is such a large blood supply to the grey 

 matter of the brain is that important bio-chemical processes 

 occur there, constituting the physiological basis of mental 

 activity. In all mental operations nervous energy is used up; 

 the neurones are the agents for the storage and liberation of 

 nervous energy ; and its liberation is the physiological basis of 

 mental activity, whether it be in simple or complex processes. 

 The neurones automatically store energy when they liberate it, 

 but there is a reserve store for emergencies. Now liberation of 

 nervous energy, that is, conversion of latent neuro-potential into 

 active neuro-potential involves oxidation ; consequently oxygen 

 is essential for the process. This is shown by the fact that un- 

 consciousness results if the cortex of the brain is deprived of 

 arterial blood for a few seconds. 



We are conscious of the external world and our own 

 personality and existence by continuous stimuli arising from 

 the external world and from our own body. If those stimuli 

 were cut off, we should lose consciousness, notwithstanding 

 that the blood supply to the cortex of the brain continues. 

 The neurones of the cortex of the brain, besides innate 

 potentiality to function, require also the stimulus from the 

 external world together with a proper supply of oxygenated 

 blood ; and this implies a sufficient number of red blood 

 corpuscles provided with an adequate quantity of the red 



