304 E. ROBERTS AND D. G. SIMONSEN 
the hemispheres (Figs. 93, 94) showed relatively low levels of this amino acid. From 
inspection of the chromatograms prepared from the extracts of the different cerebral 
areas either at 15 or 21 days of incubation it is apparent that the most marked 
difference in any detectable ninhydrin-reactive constituent from one area to another 
is in the content of GABA. The progressive increase of GABA with the age of the 
embryo is illustrated for the optic lobes of the chick in Figs. 99-106. The decrease 
in content of ethanolamine phosphate with age also is noteworthy. 
Quantitative determinations of GABA and the activity of glutamic acid decar- 


N22 


+ 

Figs. 91-98. Amino acids in extracts of chick embryo brain at 15 and 21 days of incubation 
(20 mg equivalents). Fig. 91: cerebellum, 15 days. Fig. 92: cerebellum, 21 days. Fig. 93: hemi- 
spheres, 15 days. Fig.94: hemispheres, 21 days. Fig. 95: optic lobes, 15 days. Fig. 96: optic 
lobes 21 days. Fig. 97: diencephalon, 15 days. Fig. 98: diencephalon, 21 days. y-Aminobutyric 
acid, 22; ethanolamine phosphate, 19. 
References p. 348/349 
