At the 1910 meeting defining the curie, Marie Curie insisted that it equal the activity of one gram of radium.
The curie was created as a practical unit for radioactivity and was named for the Curie family’s work. An early proposal would have based it on a much smaller amount—about 10 nanograms of radium—but Marie Curie objected that such a tiny quantity made the named unit inappropriate. She argued for the activity associated with one gram of radium.
The original concept was expressed as the quantity of radium emanation, now understood as radon, in equilibrium with one gram of radium. Later definitions tied the unit more precisely to radium-226’s activity. In 1964, the curie was fixed at 3.7 × 10¹⁰ decays per second.
The curie is now a non-SI unit. The SI unit is the becquerel, equal to one nuclear decay per second; therefore 1 curie equals 37 gigabecquerels. The question refers to the 1910 historical definition, not the later numerical refinement or the modern SI replacement.