FREE AMINO ACIDS IN ANIMAL TISSUE 30 
Un 
boxylase, the enzyme which forms GABA from glutamic acid, previously had been 
correlated with cytological changes in the developing mouse brain?’. A recent study 
has been made of the changes of the enzymes related to the metabolism of GABA 
and of the content of this amino acid in the optic lobe as a function of age of the 
embryo and the newly hatched chick?*. 
From the above results as well as from many data from our own and other labora- 
tories (refs. 28-30 and others) which have not been presented it appears that although 

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a 105 \ 4 106 
Figs. 99-106. Amino acid patterns of extracts of optic lobes of chick embryo brain (20 mg equiv- 
alents) at various times of incubation. Fig. 99: 6 days. Fig. 100: 8 days. Fig. tor: 1o days. 
Fig. 102: 13 days. Fig. 103: 17 days. Fig. 104: 19 days. Fig. 105: 20 days. Fig. 106: 21 days. 
y-Aminobutyric acid, 22; ethanolamine phosphate, 19. 
References p. 348/349 
