THE MASTIGOPHORA 



117 



upper half of the shell. The two flagella which lie in these grooves 

 pass from the body-plasm to the outside through a distinct aperture 

 in the shell, which Stein ('/8) called the " mouth-opening " ; but as 

 it serves no purpose in food-taking, Biitschli has substituted the better 

 term of flagellum fissure. 



The protoplasm of the Mastigophora usually contains chromato- 

 phores in which one or more deeply staining bodies the pyrenoids 

 may be found, and these 

 are frequently covered by a 

 shell of amylum or starch. 

 Paramylum, a food product 

 allied to starch, and various 

 particles of oil-like substance 

 are widely distributed. The 

 .latter are frequently so nu- 

 merous that the cell is fairly 

 filled with them. Upon dif- 

 fluence, these oil-like bodies 

 run together, forming glob- 

 ules of large size; or they 

 become finely divided, giving 

 to the surrounding liquid the 

 appearance of an emulsion. 

 Not infrequently the oils have 

 a characteristic odor and taste, ^ B 



Comparable to the SCent Of Oils Fig. 63. Distephanus speculum Stohr. [BORGERT.] 

 Of plants (Uroglena ameri- A ' Lateral view of skeleton. B. Surface view. 



cana, Synura uvella. Fig. 65 ). 1 



Chromatophores are widely distributed among the various Flagel- 

 lidia. They consist of clearly defined, thickened bodies, usually of 

 definite size and shape and of different shades of green, yellow, and 

 brown. Clear green chromatophores, colored by chlorophyl as in the 

 plants, occur in Euglenidae, Peranemidae, Chlamydomonadidae, 

 and Volvocina. Yellow chromatophores (colored by diatonrin, 

 as in Diatomaceae) occur in Chrysomonadidae, Cryptomonadidae, 

 among the Flagellidia, and possibly in some Dinoflagellidia ; but 

 the yellow color, when present in the latter group, frequently 

 shades off into brown. Bergh ('81), Klebs ('84), and others regarded 

 the coloring matter of the. Dinoflagellidia as pure or slightly mixed 

 diatomin, which supported the popular view that the Diatomaceae 

 and the Dinoflagellidia are closely related. Schiitt ('90), however, 

 who has made the most complete study of the coloring matter in these 



Cf. P . 62. 



