314 THE AMEBIC AN NATURALIST [Vol. LI V 



present. Some infusions will be colored a milky hue 

 from the multitudes of these forms within them. The 

 individuals of the species vary considerably in size, some 

 being no greater than 2 microns along the anterio- 

 posterior axis. The majority of the individuals, how- 

 ever, lie within the limits of 3 to 8 microns. They may 

 be recognized at once by their peculiar agitation and 

 habit of leaping or jerking about from place to place. 

 Individuals may sometimes be discovered lying quiet, 

 except for a gentle vibration— a motion which, it has 

 been suggested earlier in this paper, may be due to the 

 influence of pedesis. These quiet forms are to be found 

 usually near the edges of masses of disintegrating mate- 

 rial, where they are likely to be overlooked. The bodies 

 are often particularly hyaline, and the flagella difficult to 

 make out. Iodine (an alcoholic solution, with potassium 

 iodide, as given under No. 2, Section B of the Formulary 

 of Reagents at the end of the paper) as a stain after 

 killing was found to be the best for these minute forms. 

 In some cases the flagella could be made to take the stain 

 well, in others not. Those killed with the stain itself 

 seemed to be better colored than those stained after 

 having been killed with some other reagent. 



Gents Simromoxas Perty. 



Body leaf or ribbon-like, either flattened or more com- 

 monly twisted spirally, with one or two turns, very vari- 

 able. Kent says that these forms may even assume an 

 amoeboid form of body. Of the two flagella that arise 

 from the anterior tip of the body, one trails, one extends 

 forward and vibrates with great rapidity. 



The variable 8. angustata (Fig. 11) seems to be quite 

 common in infusions of all kinds, but particularly abun- 

 dant in those of hay, swamp grasses, and the like. 



ORDER PFIYTOMASTTGTDA 



Genus Amphimonas Dujardin. 



Body globular, either attached by a fine posterior pedi- 

 cel, or free-swimming— the latter being apparently the 



