CHEMICAL CHANGES IN HUMAN BRAIN 



451 



Milligrams 

 added perday 



12 16 20 



T/me in months 

 Fig. 2 



24 



28 



Phosphatids 



Lecithin (MacArthur and Darrah, '16), cephalin (MacArthur, 

 '16), sphingomyelin and myeUn are the principal phosphatids 

 found preformed in the brain. Some or all of these compounds 

 are present from very early fetal life (table 1). They gradually 

 increase (table 12) until myelination becomes rapid, then they are 

 formed at the maximum rate of 0.1 gram per day (table 13). 

 They continue to be formed rapidly until two years of age; after 



