280 



CLASS: MASTIGOPHORA 



organs. The three last-named orders are fairly well defined, but there is 

 more difficulty in connection with the Protomonadina and the Polymasti- 



FiG. 131. — Hcematocoecus liluvialis ( x ca. 2,500). (After Reichenow, 1910). 



A. Individual from a culture in a special medium, giving rise to forms without hsematochrome, 



The nucleus, three pyrenoids, and the stigma, as a dark rod near the right-hand margin, 

 are clearly visible. 



B. Usual form with structure obscured by hamatochrome. S, stigma scarcely visible. 



Fig. \^2.—Qonium pectorale : Colony of Sixteen Individuals, each with Two 



Flagella (X ca. 480). (From Minchin, 1912, after Stein.) 



^ , In surf ace view ; iJ, in side view; A'^, nuclei; cv., contractile vacuole; s<, stigmata. 



