The Apothecarion is a Space Marine Chapter's medical and bio-engineering department. Their most important duty is the preservation of the Chapter's gene-seed, the only means by which new Space Marines may be created. The life or death of a Chapter is therefore dependent upon their Apothecarion.
Each Apothecarion is typically headed by a Chief Apothecary and permanently staffed by a number of Apothecaries. These Apothecaries rarely take to the field of battle themselves. Their primary function is the maintenance of the various bio-vaults, each one containing a gene-seed ready for implantation. These gene-seeds are extensively monitored, with only the healthiest kept, while those showing signs of mutation are removed to avoid further contamination. The Apothecaries are also responsible for screening new Aspirants for any physical deficiencies, before continuing on the process of creating a new Space Marine, and are responsible for maintaining routine medical and surgical duties to ensure the Chapter's warriors are in fighting shape. For accurate record-keeping the Apothecarion will maintain vast memory banks which contain the extensive genetic history of their Chapter.
In addition to the Apothecarion's staff, each Company has its own Apothecary. In the field, these Apothecaries are responsible for administering battlefield medical care, including emergency surgery. However, their most important duty is the recovery of the gene-seed from fallen battle-brothers, removing the progenoid organs from their body and returning them to the Apothecarion for the next recruit.