CHLAMYDOMONAS 



53 



plasm, within which a single nucleus resides. The 

 chloroplast is thicker at the posterior end the bottom 

 of the cup where it encloses a spherical pyrenoid. The 

 fore-part of the cell is colourless, being occupied by clear 

 protoplasm, in which one or two vacuoles may be seen 

 appearing and disappearing. A red or brownish pig- 

 ment, or " eye " spot, is also visible at one side of the 

 body towards the front. This tiny one-cell plant 

 swims in a jerky fashion, rotating on 

 its long axis as it proceeds, its direc- 

 tion being towards a light of moder- 

 ate intensity; and it is suggested 

 that the pigment spot has something 

 to do with the plant's sensitiveness 

 to light. But how is it enabled to 

 swim ? If we watch a cell that has 

 come to rest, we may be able to see 

 that a pair of flagella issue from the 

 colourless protoplasm to the fore. 

 These exceedingly fine lashes are 

 more easily observed when the cell 

 is stained, say, by iodine. It is 

 by lashing the water with its two 

 flagella that Chlamydomonas swims. 

 Animal-like as this organism is in its movements, it 

 is certainly a plant. It has no mouth; it cannot ingest 

 solid food; it must feed upon the products of carbon 

 assimilation and salts in solution, all its requirements 

 reaching it in solution through its permeable wall of 

 cellulose. 



Even in so small a plant as Chlamydomonas, both 

 asexual and sexual modes of reproduction are apparent. 



HIGHLY MAGNIFIED. 



(STEASSBURGEB.) 



g, Cilia ; v, vacuole; chr, 



ch ioroplast ; k, nucleus; 

 , eye-spot; py, py- 



