LIPIDS PRESENT IN BRAIN AND NERVOUS TISSUE 759 



early as the second day, and sphingomyelin appeared eight to sixteen days 

 after birth. 



Waldemar Koch, 306 many years ago, demonstrated similar variations in 

 the composition of the human brain as related to age. His data are sum- 

 marized in Table 15, while those of Schuwirth 301 are included in Table 16. 



Although neutral fat does not occur in appreciable amounts in adult 

 brain tissue, definite quantities are present in the brain of the newborn. 

 Tuthill 307 reported that the fat content of the brains of forty-six infants 

 ranging in age from newborn to two years contained varying amounts of 

 neutral fat. Fat was found around the blood vessels and the glial cells of 

 the centrum ovale, corpus callosum, and white substance of the lower 

 part of the gyri of all infants who had died at the age of less than four 

 months. The disappearance of the fat after four months occurred con- 

 comitantly with the completion of myelinization. Fat formed around the 

 large subcortical vessels from the first month to the second year of life. 



In an extension of their studies on the composition of nervous tissue, 

 Johnson and co-workers 308 noted that the water content of both white and 

 gray matter of infant brain was greater than that of adult brain. In the 

 infant, the water content of the gray matter, also, was greater than that of 

 white matter. In the adult brain, a higher concentration of free choles- 

 terol, cerebroside, and sphingomyelin was found both in the gray and in the 

 white matter. Less lecithin was present in the adult brain than in that of 

 the infant. 



Gorodisskay 309 found no definite relation between age and the composi- 

 tion of the brain of mature individuals up to forty-five years of age. In 

 older individuals, the unsaturated phospholipids and proteins decreased, 

 while cholesterol increased. No change was observed in the level of satur- 

 ated phospholipids and of cerebrosides. The changes in composition were 

 most marked in the association centers. 



c. The Effect of Brain Areas on Brain Lipids. Although it has been 

 demonstrated that there is a marked variation in composition between the 

 gray and the white matter, Gorodisskay 309 was able to prove that variations 

 in composition are concomitant with variations in psychic function. 

 Cholesterol was the component most affected. Saturated phospholipids 

 were somewhat less variable, while the unsaturated phospholipids showed 

 the least variability. Based upon total nitrogen as a reference, the lowest 



306 W. Koch, Z. physiol. Chern., 63, 432-442 (1909). 



307 C. R. Tuthill, Arch. Pathol., 25, 336-346 (1938). 



308 A. C. Johnson, A. R. McNabb, and R. J. Rossiter, Biochem. J., 44, 494-498 (1949). 



309 H. Gorodisskay, Biochem. Z., 164, 446-480 (1925). 



