The Primus Medicae was a senior Consular officer of the Legiones Astartes charged with overseeing a Legion's Apothecarion and the care of its warriors during the Great Crusade and the Horus Heresy. As the ranking Apothecary, this officer bore responsibility not only for battlefield medicine but for the sacred stewardship of the Legion's gene-seed.
Beyond tending wounds, the Primus Medicae directed the recovery of the progenoid glands from the fallen, ensuring that the genetic legacy of the dead might be passed to future generations of Space Marines. This duty made the role a guardian of the Legion's very continuity, a matter of profound importance to every Legion's survival.
As a specialist Consul within a Space Marine Legion, the Primus Medicae commanded deep respect, and among the gene-cursed Blood Angels their vigilance carried a graver weight still. During the Heresy, as Legions bled one another on a scale never before seen, the preservation of gene-seed became a desperate concern, and the Primus Medicae's work grew ever more vital.