u8 



THE PROTOZOA 



forms, disproved this view by showing that the coloring matter is quite 

 distinct from diatomin and is peculiar to the Dinoflagellidia. He suc- 

 ceeded in extracting three substances: (i) phycopyrrin, similar to the 

 brownish red coloring matter of the Floridese and Phasophycacese 

 among the plants, and like this, soluble in clear water ; (2) peridinin, 

 like chlorophyl soluble in alcohol, but of quite different spectrum ; 

 and (3) chlorophyllin, a substance more like chlorophyl, but difficult 

 to isolate. 



The shape and size of the chromatophores vary considerably in 

 different species, but are fairly constant for the same species. They 

 increase by simple division. The pyrenoids, which seem to be the 

 centre of starch formation, are sometimes quite naked (Euglena), 



..../_.. 



Fig. 64. — A. Gymnodlnlum ovum Schiitt. B. Peridtnium dwergens Ehr. f t transverse furrow 

 with (A) flagellum. [Schutt.] 



sometimes covered by a shell of paramylum, which apparently differs 

 from starch only in its reaction to iodine. The paramylum granules 

 are round, rod-like, or ring-form bodies. Pure starch is also recorded 

 as a product of non-colored, saprophytic forms (Chilomonas, Poly- 

 toma, etc.). In many of the Mastigophora, especially in those holding 

 chromatophores, there may be an intense red coloring matter, in the 

 form of fine drops, scattered throughout the protoplasm. These consist 

 of oil particles impregnated with a deep red pigment, — hcematoclirome, 

 — and the same substance is found in the so-called "eye-spots," or 

 stigmata, which are supposed to be more sensitive to light than other 

 parts of the protoplasm, although Engelmann's ('82) results show that, 

 in Euglena at least, the clear plasm just in front of the stigma is more 

 definitely involved. In many cases the structures accompanying the 

 stigmata are so strikingly analogous to the visual organs of higher 



