In the Algae such a cell consists essentially of: (1) a mass of protoplasm provided with (2) a nucleus and (3) an assimilating apparatus consisting of a colored protoplasmic body, called a chromatophore, the pigment of which in the pure green forms is chlorophyll, and which may then be called a cliloroplast.
The separate layers of the starch-grain are deposited on it by the activity of the chrmatophore, and according to Meyer the grain is always surrounded by a thin layer of the chromatophore which completely separates it from the cytoplasm.
Occupying as these algae do perhaps the lowest grade of plant life, it is a matter of interest to ascertain whether a nucleus or chromatophore is differentiated in their cells, or whether the functions and properties of these bodies are diffused through the whole protoplast.
Fischer has further established the fact that the peripheral mass, which is a hollow sphere in spherical cells, and either a hollow cylinder or barrel-shaped body in filamentous forms, must be regarded as the single chromatophore of the Cyanophyceous cell.
Embedded in the chromatophore, much in the same way as the nucleus is embedded in the cytoplasm, are the pyrenoids.
Each cell contains a flattened chromatophore of a brown or yellow colour.
With reference to the existence of a chromatophore, he with others finds the colouring matter localized in granules in the peripheral region, but does not consider these individually or in the aggregate as chromatophores.
Chlamydomonas sp., unicellular; chr.,chromatophore; p.,pyrenoid; H.
In Ulva and Mesocarpus the chromatophore is a single plate, which in the latter genus places its edge towards the incident light; in Spirogyra they are spiral bands embedded in the primordial utricle; in Zygnema they are a pair of stellate masses, the rays of which branch peripherally; in Oedogonium they are longitudinally-disposed anastomosing bands; in Desmids plates with irregular margins; in Cladophora polyhedral plates; in Vaucheria minute elliptical bodies occurring in immense numbers.