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Total and free amino acid composition of germinating cotton seeds (Gossypium hirsutwm L.) was determined. The germinating seeds were separated into cotyledon and developing axis fractions daily and the composition of each tissue was summed to get the whole seed composition. By separating the developing seeds into these two tissue fractions, and determining total and free amino acids, a balance sheet was developed for each amino acid. This technique allowed changes in distribution with time of each amino acid to be followed in each tissue. Data for total content and amount in protein of each amino acid are presented. Asparagine increased in the whole seed, and most of this increase was found in the free pool of the developing axis. Other amino acids (eg. arginine, glutamic acid) increased in the free pool but showed an over-all decrease, indicating that they were being metabolHzed. Amino acid contents of storage and nonstorage protein isolates were determined.The free amino acid composition ofdeveloping and germinating cotton seeds and of young cotton roots has been determined (6,11,17). The reports show that asparagine is very prominent in the developing embryo as well as in the germinating seedling. Aspartic acid, however, is not nearly as prevalent in the protein as the prevalence of the amide might suggest. In various species others have suggested that asparagine is the predominant transport form of reduced N and that metabolic transformations between asparagine and other forms commonly occur at source and sink sites (2, 14). We determined the amino acid composition ofgerminating cotton seeds and of storage and nonstorage protein isolates from them. By separating the developing axis from cotyledons, we were able to follow the course of amino acid distribution from the storage organs into the newly synthesized axial regions. (1), and analyzed on the amino acid analyzer with a two-column procedure using lithium citrate buffers to separate the acidic and neutral amino acids (5), and sodium citrate buffers to separate the basic amino acids (1). The lithium column worked well for standard solutions but biological samples presented some difficulty, because glutamic acid and glutamine appear as consecutive peaks in this system. When glutamic acid was present in much greater amounts than glutamine, the glutamine peak was smothered and appeared as a shoulder on the glutamic acid peak. That happened in this experiment so the results are presented as glutamic acid plus glutamine. Storage and Nonstorage Proteins. Storage and nonstorage protein isolates were extracted from Deltapine 16 cotton seeds as described by King and Lamkin (13). The amino acid composition of hydrolysates of the separated isolates was then determined as previously described. MATERIALS AND METHODS RESULTSWeight and Size. Changes in weight and size of the developing seedlings are summarized in Table I. The axes increased 20-fold in fresh weight and length, and more than 4-fold in dry weight over the 4 days of measurement; during the same peri...

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