EYE-SPOT Aj>JD PLAGELLUM IN EFGLENA VIRIDIg. 465 



I find that the chlorophyll-bodies are capable of assuming 

 different shapes — spherical, oval, elongate, and ribbon-like ; and 

 to this may be due the different views as to their nature taken 

 by various observers. 



The cell usually contains a large number of grains of a starch- 

 like composition {paramylum), which are not coloured blue by 

 iodine, and are therefore not pure starch. They possess a very 

 definite and characteristic structure, which is correctly figured 

 by Klebs *, presenting some resemblance to the structure of a 

 typical starch grain in being composed of laminae, but differing 

 from the starch grain in this, that the laminae are not concentric, 

 and present the appearance of flat plates laid one upon the 

 other. 



These paramylum grains may be found in any part of the cell, 

 but under normal conditions are generally more numerous in 

 the region of the chlorophyll-bodies. In cells kept in the 

 dark, in a good nutrient solution such as a dilute solution of 

 potato-starch t, the chlorophyll-bodies become pushed to the 

 posterior end of the cell, whilst the anterior two-thirds of the 

 cell become filled with a mass of paramylum grains. This 

 results in the production of the so-called "white" or " colour- 

 less " forms. 



The nucleus is usually found at the posterior end of the cell, 

 but it may occur in the middle, or very rarely at the anterior 

 end; in the "white" forms just described, it is found between 

 the chlorophyll-bodies and the paramylum grains. In normal 

 cells the nucleus is posterior to the chlorophyll-bodies ; in the 

 " white " forms it is anterior to them. It can be very easily seen 

 in the living cell, and with care its structure can be made out. 

 In oemic acid, and other hardening and preserving fluids, the 

 structure is brought out very clearly. It consists of a central 

 spherical nucleolus surrounded by a granular network. 



The anterior end of the cell has a depression leading into a 

 narrow tube or gullet, out of whicli the flagellum passes. On 

 the dorsal side of the gullet is a distinct eye-spot, and near it is 

 a large clear space, called the principal vacuole ; and on one 

 side of this a single, pulsating vacuole. 



* Loc. cit. See plate ii. figs. 8 a, 8 i, 8 c. 

 t Xhawkiiie, I. c. 



