Cross sections for production of Li and Be isotopes in the ..cap alpha..(..cap alpha..,pn)/sup 6/Li, ..cap alpha..(..cap alpha..,p)/sup 7/Li, and ..cap alpha..(..cap alpha..,n)/sup 7/Be reactions have been measured at 198.4 MeV. These measurements are relevant to the understanding of light-element nucleosynthesis in galactic cosmic ray interactions with the interstellar medium. The data indicate that beyond energies of about 250 MeV, the ..cap alpha..+..cap alpha.. reaction does not contribute to the natural abundance of lithium, reinforcing theories which produce /sup 6/Li in cosmic ray processes and most of nature's /sup 7/Li in the big bang. In addition, ..cap alpha..+..cap alpha.. elastic scattering data obtained in these experiments have been analyzed in terms of the optical model, and the results are compared with lower-energy systematics.