The following sentences by Reichert and Brown seem to indicate that this may be true for the crystals of hemoglobin.
"Manhood of Humanity."
Alfred Korzybski
Bernard's study of the change that had taken place in the blood showed that the hemoglobin of the red blood-cells had united with the carbonic oxide present in the lungs to form a stable compound.
"Makers of Modern Medicine"
James J. Walsh
This idea was overthrown by the discovery that the carbonic oxide combination with hemoglobin was very permanent.
"Makers of Modern Medicine"
James J. Walsh