The second half of the paper applies our general results to the concrete setting of 625&_mathId=si5.gif&_user=111111111&_pii=S0022404915002625&_rdoc=1&_issn=00224049&md5=17e1539f4af9b0021cf144cc8e1a75bf" title="Click to view the MathML source">G=GL(∞) and 625&_mathId=si6.gif&_user=111111111&_pii=S0022404915002625&_rdoc=1&_issn=00224049&md5=273b33601e92372ae33ff68780f2f586" title="Click to view the MathML source">g⁎=M(∞), the space of infinite-by-infinite complex matrices with arbitrary entries. We use the Poisson structure of 625&_mathId=si24.gif&_user=111111111&_pii=S0022404915002625&_rdoc=1&_issn=00224049&md5=ca1bb1fad64b9672965d733037d6bfeb" title="Click to view the MathML source">g⁎ to construct an integrable system on 625&_mathId=si7.gif&_user=111111111&_pii=S0022404915002625&_rdoc=1&_issn=00224049&md5=0c5c860f789bfe5d28458bdbfffcf0ea" title="Click to view the MathML source">M(∞) that generalizes the Gelfand–Zeitlin system on 625&_mathId=si8.gif&_user=111111111&_pii=S0022404915002625&_rdoc=1&_issn=00224049&md5=b8e5ab9550129066043f4c02472648bf" title="Click to view the MathML source">gl(n,C) to the infinite-dimensional setting. We further show that this integrable system integrates to a global action of a direct limit group on 625&_mathId=si7.gif&_user=111111111&_pii=S0022404915002625&_rdoc=1&_issn=00224049&md5=0c5c860f789bfe5d28458bdbfffcf0ea" title="Click to view the MathML source">M(∞), whose generic orbits are Lagrangian ind-subvarieties of the coadjoint orbits of 625&_mathId=si9.gif&_user=111111111&_pii=S0022404915002625&_rdoc=1&_issn=00224049&md5=63ea5bb2bf3089d0a860213405287ae3" title="Click to view the MathML source">GL(∞) on 625&_mathId=si7.gif&_user=111111111&_pii=S0022404915002625&_rdoc=1&_issn=00224049&md5=0c5c860f789bfe5d28458bdbfffcf0ea" title="Click to view the MathML source">M(∞).