Cystine Glucose blood agar is also known as Cystine Heart Agar. Francis developed blood-dextrose-cystine agar after determining F. tularensis would only grow on an artificial medium supplemented with sulfhydryl compounds (i.e., cystine). F. Tularensis is extremely meticulous organism that requires cystine to grow at its best. To honor the achievements of all time of Francis in the field of understanding the disease it was named Francisella Tularensis. The hemoglobin-rich medium is suggested to cultivate Francisella Tularensis. Without enrichment supplies, it facilitates the growth of cocci gram-negative and other pathogenic organisms.