Chlamydomonas sp., unicellular; chr.,chromatophore; p.,pyrenoid; H.
Sometimes several pyrenoids occur in each chloroplast.
The pyrenoid seems to be of proteid nature and gelatinous consistency, and to arise as a new formation or by division of pre-existing pyrenoids.
When carbon-assimilation is active, starch-granules crowd upon the surface of the pyrenoid and completely obscure it from view.
They are composed of a homogeneous proteid substance, and often contain albuminoid or proteid crystals of the same kind as those which form the pyrenoid.