36 MANUAL OF ZOOLOGY SKPT. i 



the sfigwa (/>^.), formed of a pigment allied to chlorophyll 

 and called h&matockrome. It seems probable that the 

 stigma is a light-perceiving organ or rudimentary eye. 



Euglena is nourished like a typical green plant : it de- 

 composes the carbon dioxide of the air dissolved in the water, 

 assimilating the carbon and setting free the oxygen. Nitrogen 

 and other elements it absorbs in the form of mineral salts 

 in solution in the water. But it has also been shown that 

 the movements of the flagellum create a whirlpool by 

 which minute fragments are propelled down the gullet and 

 into the soft internal protoplasm. There seems to be no 

 doubt that in this way minute organisrrs are taken in as 

 food. Euglena thus combines the characteristically animal 

 (holozoic) with the characteristically vegetable (holophytic) 

 mode of nutrition. 



Sometimes the active movements cease ; the animal 

 comes to rest and surrounds itself with a cyst or cell-wall 

 of cellulose (the characteristic material of the cell-wall of 

 plants), from which, after a quiescent period, it emerges 

 to resume active life. It is during the resting condition 

 that reproduction takes place by the division of the body 

 in a median plane parallel to the long axis (G). Under 

 certain circumstances multiple fission takes place, and 

 flagellulce, i.e., young provided with flagella, are produced, 

 which, sometimes after passing through an amoeboid stage, 

 develop into the adult form. 



In the other Mastigophora the body may have a shape 

 similar to that of Euglena, or may be longer and narrower, 

 or, on the other hand, may be short and thick, ovoid or 

 globular. Anterior and posterior ends are nearly always 

 distinguishable, the former being that which is directed 

 forwards in progression. Usually there are distinct dorsal 

 and ventral surfaces, the former being that which is habitually 



