A culture medium is used for the growth, storage and transport of microorganisms in the laboratory. It can be solid or liquid. Fastidious organisms will not grow without specific nutrients, so the media must be enriched to encourage their growth. For example, blood agar is used to grow bacteria, such as several species of streptococcus. Chocolate agar is a medium comprised of hemoglobin and other supplements, which is used to isolate Haemophilus and Neisseria.