700 THE AMERICAN NATURALIST. [VOL. XXXIX. 



We may pass now to the peripheral region of the cell which 

 holds the blue-green coloring matter of the Cyanophyceae. A 

 number of investigators, as Wager (103), Kohl (103), Hegler 

 (:oi), and Hieronymus ('92), have held that this pigment was 

 contained in minute granules distributed throughout the cyto- 

 plasm under the cell wall. These granules have at times been 

 termed chromatophores or plastids and Hegler has proposed for 

 them the name cyanoplastids. Other authors, especially Fischer 

 ('97), Nadson ('95), Palla ('93), and Zukal ('92) have been unable 

 to find these color-bearing granules and have believed the color- 

 ing matter to be uniformly diffused throughout the peripheral 

 region of the cell. Fischer has made a particularly thorough 

 study of the reactions of the pigmented region to various acids 

 in comparison with the chromatophores of higher algae and con- 

 cludes that no plastids are present but that the color is held in a 

 hollow cylindrical or spherical outer layer of protoplasm which 

 may be termed a chromatophore. Olive supports Fischer, 

 approaching the subject from a very different point of view. If 

 minute plastids are present they should be visible in fixed and 

 stained material and Olive is unable to find any trace of Hegler's 

 cyanoplasts. The granules .of the outer region of the protoplast 

 seem to be colorless inclusions. 



Perhaps the most confused part of the discussion on the 

 structure of the cell of the blue-green algae is that which deals 

 with certain inclusions. There are apparently two sorts which 

 are very common in the cells: (i) the cyanophycin granules 

 (Borzi) and (2) the slime globules. The cyanophycin granules 

 are very apt to lie along the cross walls in filamentous forms or 

 in other peripheral regions of the cell. They are generally 

 believed to be a form of food material and it has been suggested 

 that they are the first visible product of photosynthetic processes, 

 but their chemical nature is under dispute. The slime globules 

 lie more frequently in the interior region of the cell close to the 

 nucleus and frequently within this structure. They have been 

 termed nucleoli by some authors and also confused with chro- 

 matin. Besides these two bodies, other minute globules have 

 been described as oil or fat and some remarkable crystalloid 

 structures have been figured, especially by Hieronymus ('92)- 



