On the picture above one half of the Cephalotus pitcher is cut away allowing us to see the pitcher mouth from the inside including the curved teeth of the peristome, the dark-violet internal collar, and the dark-brown boat-shaped gland patch where the digestive glands are located. On the outside of the pitcher the middle wing and a cross section of one of the lateral wings are seen. The red coloration of the pitcher and the dark boat-shaped gland patches cause greater absorption of heat radiation. It increases tissue temperature, and it has been suggested this is an advantage to the activity of the digestive enzymes. Others are of the opinion that the dark coloration of the pitcher protects the enzymes in the pitcher fluid from photo-oxidation.