An albumin present in some life forms (notably fireflies) that under the influence of the enzyme luciferase, exhibits bioluminescence. When luciferin (along with luciferase) comes in contact with adenosine triphosphate, present in all living cells, a chemical reaction occurs that causes luminescence. By correlating its intensity with the amount of adenosine triphosphate present, a means of measuring bacterial growth is obtained. Applications in biomedical technology are envisaged for this so-called luminescence biometer.